portion-spec

---
name: portion-spec
description: Turns each dish into a one page spec sheet with weighed components, a named serving tool, a photograph and a tolerance, so the same plate leaves the pass whoever is on. Use when food cost moves without the prices moving, when customers say the portions changed, or when a dish only comes out right if one chef is in.
---

# Get the same plate out of the pass on a Tuesday as on a Saturday, whoever is cooking

You give this the dish, one real plate of it made during service, and a set of scales. You get back a one page spec for that dish: every component weighed, a named tool that produces that weight without anyone thinking about it, a photograph taken from two angles, the tolerance the kitchen is held to, and the order quantity that portion implies. It is written to be pinned above the pass and used by a chef who started on Monday.

## What it does

1. **Do the ten dishes that matter before you do the other forty.** Rank the menu by portions sold multiplied by plate cost, take the top ten, and start there. Those are the dishes where a twenty gram drift is real money and where a customer notices a change. A kitchen that tries to spec an entire menu in one go produces forty half-finished sheets and uses none of them; a kitchen with ten finished sheets pinned up will have the other forty by Christmas because the habit sticks. Add to the ten anything that has generated a complaint about size, anything with an expensive protein, and anything a member of staff has said "depends who's on" about. Write the list, date it, and work down it.

2. **Build the spec from a weighed plate, never from the recipe.** Have the dish made during service by whoever normally makes it, then weigh every component separately before it goes out: protein, starch, vegetable, sauce, garnish, the bread on the side. Do this three times across three services, with different people if you can, and write all three weights down. The recipe says what someone intended two years ago; the three plates say what the kitchen does now, and the gap between the two is usually most of the problem. The open textbook *Basic Kitchen and Food Service Management* puts the consequence bluntly: "if one order of bacon and eggs goes out with six rashers of bacon and another goes out with three rashers, it is impossible to determine the actual cost of the menu item." Set the spec weight from the three plates and the cost card, not from either alone.

3. **Give every component a tool, so nobody has to remember a number.** A weight written on a sheet is a hope. A number 12 scoop, a 60ml ladle, a 30ml jigger, a portioned bag, a ring mould and a set of scales on the section are how the weight actually happens. The same textbook: "simple methods to control portion include weighing meat before it is served, using the same size juice glasses when juice is served, counting items such as shrimp, and portioning with scoops and ladles that hold a known volume", and "standard portions are assured if the food operation provides and requires staff to use such tools as scales, measured ladles, and standard size scoops." For each component write the tool by its number or capacity, not by description: "one number 16 scoop, levelled" rather than "a scoop of mash". Where no tool exists, the component goes on the scales and the sheet says so.

4. **Photograph the finished plate twice and put both pictures on the sheet.** One from directly above, showing the layout and the coverage, and one from the seated diner's eye line, because that is the view that decides whether the portion looks generous. Shoot it on the plate you actually use, under the light you actually have, with nothing tidied out of shot. The textbook notes that "some operations also have photographs of each item posted in the kitchen area to remind workers what the final product should look like", and a photograph settles arguments a number never will: a chef can dispute 180 grams and cannot dispute a picture. Date the photograph, and retake it whenever the plate, the garnish or the supplier changes.

5. **Write one page per dish, and put a tolerance on it.** The sheet carries: dish name, date, section, plate or bowl used, then a row per component with the spec weight or count, the tool, and the tolerance. Give the main protein a tight tolerance, plus or minus five per cent, and the garnish a loose one, because a chef who is told everything is critical will treat nothing as critical. Underneath: the finished plate weight, the plate cost at spec, and one line naming the component that costs the most, so everyone knows which one to be careful with. A standardised recipe, as the textbook has it, "is one that holds no surprises ... no matter who follows the directions", and a sheet nobody can follow at eight o'clock on a Saturday is not one.

6. **Do the drinks separately, because the sizes are set in law and not by you.** For consumption on the premises, the Weights and Measures (Intoxicating Liquor) Order 1988 provides that beer and cider are sold "only in a quantity of ⅓ pint, ½ pint, 2/3 pint or a multiple of ½ pint", that gin, rum, vodka and whisky are sold in "25 ml or 35 ml" or a multiple, and that wine by the glass is sold "only in, or in a multiple of ... 125 ml and 175 ml". Separately, the mandatory licensing conditions require that "beer or cider - half pint", "gin, rum, vodka or whisky - 25ml or 35ml" and "still wine in a glass - 125ml" are available, and that the responsible person "must also make their availability clear on menus, price lists or other printed material". Write the house measure on the spec, check the glassware is stamped for it, and check the wine list shows 125ml. If the site runs more than one spirit measure, ask trading standards before you print it.

7. **Prove the spec with a blind test before you call it done.** Give the sheet and the tools to three people who did not write it, including whoever is newest, and have each of them plate the dish without being watched. Weigh all three plates. If all three land inside the tolerance, the spec works. If they do not, the spec is wrong, not the people: a component with no tool, a tolerance nobody can hit with the equipment on the section, an instruction that assumes knowledge the newest person does not have. Fix the sheet and test again. This is the step everyone skips, and skipping it is why most portion control folders are full of documents that were correct on the day they were written and have never been used since.

8. **Turn the spec into an order quantity, so the ordering stops being a guess.** Once the portion is fixed and the yield is known, the quantity to buy is arithmetic: "quantity needed = (number of portions × portion size) ÷ yield percentage". To serve fifty 250g portions of pork loin at a 52% yield, "= 12.5 kg ÷ 0.52 = 24.03 kg", so just over 24 kilograms of untrimmed loin. Print that line on the spec sheet with the dish's own yield in it. It makes the sheet useful to the person ordering as well as the person plating, which is the thing that keeps it on the wall, and it removes the standing argument about whether the kitchen over-ordered or the portions got bigger.

9. **Name an owner, set the re-check, and list what makes the sheet wrong.** One name and one date at the top. Then the triggers: a new supplier, a changed pack or cut, a new plate, a recipe change, a price change that moves the plate cost, and any complaint about size. Add a standing re-check, one dish a week weighed at random during service and the result written on the sheet, which takes about four minutes and is the only thing that stops the whole set drifting back. If the business is one that has to display calories, note on the sheet that the declared figure relates to "a single portion of the food", so a spec change and a calorie figure are never allowed to move independently of each other.

## Then it checks

1. Every spec sheet shows three weighed plates from three separate services with their dates, and the spec weight is reconciled against both those plates and the dish's cost card.
2. Every component on every sheet names a specific tool by number or capacity, or states that it goes on the scales, and no component is described only as a spoonful, a handful, a drizzle or a scoop.
3. Both photographs are on the sheet, taken from above and from the diner's eye line, on the service plate, with a date on each.
4. Every component has a stated tolerance, the main protein's tolerance is tighter than the garnish's, and the finished plate weight and the plate cost at spec both appear.
5. Drinks specs name the house measure, that measure is one of the quantities permitted for consumption on the premises, and the sheet records that the smaller measures required by the mandatory licensing conditions are shown on the menu or price list.
6. The blind test has been run with three people who did not write the sheet, all three results are recorded with dates, and any sheet where a result fell outside tolerance shows what was changed and a second set of results.

Any check fails: name it, redo that step once. Failed twice: say what is wrong and stop.

## Rules
- Public information only.
- Never invent a fact, a number or a quote.
- Anything sent in someone's name says whose name it is.
- Never set a spec weight from the recipe alone. The recipe is what was intended; the plate is what the customer gets, and the point of the sheet is to close that gap rather than to record the intention again.
- Never write a portion as an instruction without a tool. "A generous ladle", "a good handful" and "a drizzle" are the four words that make a spec sheet decorative, because two people reading them produce two different plates and both believe they followed it.
- Never cut a portion quietly to fix a food cost problem. It is the change a regular notices fastest, it is the one they tell other people about, and the money it saves is smaller than the money it costs. Change the price, the dish or the supplier where you can, and if the portion has to move, move it openly with the menu description.
- Never let a drinks spec be set by what fits the glass. The permitted quantities for on-premises sales are fixed by weights and measures law, and the glassware has to follow the measure rather than the other way round.
- This output is a working document prepared for the owner's environmental health officer, their trading standards service or their accountant to check before it is relied on. It records weights, tools and published measures. It is not advice on weights and measures law, on your premises licence, or on calorie declaration.

## Built from
- BC Cook Articulation Committee, "Basic Kitchen and Food Service Management", BCcampus Open Education, 2015, CC BY 4.0, https://opentextbc.ca/basickitchenandfoodservicemanagement/chapter/controlling-food-costs/ and the Yield Testing and Cooking Loss Test chapters, read 14 September 2026: the five standards behind the whole sheet, the portion control record that steps 3 and 5 are modelled on, the bacon and eggs example, the tool list, the photograph practice, and the ordering formula in step 8.
- The Weights and Measures (Intoxicating Liquor) Order 1988, SI 1988/2039, https://www.legislation.gov.uk/uksi/1988/2039/body/data.xht?view=snippet&wrap=true, read 14 September 2026: the permitted quantities for beer, cider, spirits and wine by the glass used in step 6.
- Home Office, "Guidance on Mandatory Licensing Conditions", version 1.0, 29 August 2014, https://assets.publishing.service.gov.uk/media/5a7dbccde5274a5eaea66081/2014-08-29_MC_Guidance_v1_0.pdf, read 14 September 2026: the small measures that must be available, and the requirement to make their availability clear on menus and price lists, which is why step 6 checks the wine list as well as the glassware.
- The Calorie Labelling (Out of Home Sector) (England) Regulations 2021, SI 2021/909, in force 6 April 2022, https://www.legislation.gov.uk/uksi/2021/909/made, read 14 September 2026: the single portion basis that ties a declared calorie figure to the spec, and the reason step 9 will not let the two move separately.

# portion-spec

## You are given
A folder from a UK restaurant, pub, cafe, bar or hotel containing any of: a till or EPOS sales export with dish names and portions sold for a stated period, a plate cost or dish costing file (CSV or XLSX), the weighing sheets from service (photographed paper, a CSV or a typed list) giving each component of each plate weighed separately with the date and the service, photographs of the finished plates, a list of the portioning tools on each section with their numbers and capacities, yield figures from trimming or cooking loss tests, the blind test results, and a note of any complaint about portion size.

For drinks, the owner also states in writing the house measure for each drink type, and the inputs carry the permitted quantities and the mandatory licensing conditions as supplied text. Codex records what is stated and what is supplied. It never states, selects or corrects a measure.

Claude picks the ten dishes, sets the tolerances and judges whether a spec can be executed on a Saturday. Codex builds the sheets from the weights.

## Produce
Write into an `output/` folder next to the inputs:

1. `portion-priority.csv` with columns in this order: `rank`, `dish`, `section`, `portions_sold`, `period_start`, `period_end`, `plate_cost_gbp`, `cost_weighted_sales_gbp`, `complaint_flag`, `expensive_protein_flag`, `depends_who_is_on_flag`, `in_top_ten`, `source`.
   `cost_weighted_sales_gbp` = `portions_sold` x `plate_cost_gbp`. Sorted by `cost_weighted_sales_gbp`, highest first. The three flags are `yes` or `no`, taken from the inputs only.
2. `weighed-plates.csv` with columns in this order: `dish`, `plate_no`, `service_date`, `service`, `plated_by_role`, `component`, `weight_g_ml_or_count`, `unit`, `weighed_by`, `source_sheet`. One row per component per plate. `plate_no` is 1, 2 or 3.
3. `component-spec.csv` with columns in this order: `dish`, `component`, `component_type`, `plate_1`, `plate_2`, `plate_3`, `unit`, `mean`, `spread`, `spread_pct`, `cost_card_quantity`, `variance_to_cost_card`, `spec_quantity`, `spec_basis`, `tool`, `tool_source`, `tolerance_pct`, `tolerance_absolute`, `price_per_base_unit_gbp`, `line_cost_at_spec_gbp`.
   `component_type` is one of `protein`, `starch`, `vegetable`, `sauce`, `garnish`, `bread`, `other`.
   `spec_basis` is one of `three weighed plates reconciled to the cost card`, `fewer than three weighed plates`, or `cost card only, no plate weighed`.
   `tool_source` names the tool list the tool was read from, or reads `goes on the scales`.
4. `spec-sheet-<dish-slug>.md` for each dish, one printable A4 page ready to pin above the pass: the dish name, the date, the named owner of the sheet, the section, the plate or bowl used, then the component table with `Component`, `Spec quantity`, `Tool`, `Tolerance`; then the two photographs referenced by filename with the date on each and the angle each was taken from; then rows labelled `Finished plate weight`, `Plate cost at spec (GBP)`, `Highest cost component`, `Order quantity line`; then the re-check triggers and the re-check date.
5. `blind-test.csv` with columns in this order: `dish`, `test_date`, `tester_role`, `wrote_the_sheet`, `component`, `quantity_produced`, `unit`, `spec_quantity`, `tolerance_absolute`, `inside_tolerance`, `sheet_change_made`, `retest_date`, `retest_quantity`, `retest_inside_tolerance`.
   `wrote_the_sheet` is `yes` or `no`. Any `yes` row is reported as a finding, because the test is only valid with three people who did not write the sheet.
6. `order-quantities.csv` with columns in this order: `dish`, `component`, `portion_size`, `unit`, `portions_required`, `yield_pct`, `yield_source`, `quantity_needed`, `quantity_unit`, `formula_shown`.
   `quantity_needed` = (`portions_required` x `portion_size`) / (`yield_pct` / 100). `formula_shown` writes the arithmetic out with the real numbers in it, for example `50 x 250g = 12.5 kg / 0.52 = 24.03 kg`.
7. `drinks-measures.csv` with columns in this order: `line`, `drink_type`, `house_measure_as_stated_by_owner`, `stated_by`, `date_stated`, `permitted_quantities_as_supplied`, `source_of_permitted_quantities`, `glassware_stamped_for_the_measure`, `smaller_measure_shown_on_menu_or_price_list`, `where_shown`, `question_for_trading_standards`.
   The last three are `yes`, `no` or `not checked`. `question_for_trading_standards` is written only where the stated measure is not among the permitted quantities supplied, or where the site runs more than one spirit measure, and it is phrased as a question, never as a finding of breach.
8. `not-weighed.csv` with columns: `dish`, `component`, `what_is_missing`, `effect`.
   `what_is_missing` is one of `no weighed plate`, `fewer than three weighed plates`, `no tool`, `no cost figure`, `no photograph above`, `no photograph at eye line`, `no yield figure`, `no tolerance supplied`.
9. `README.md` - the files read, the number of dishes specced, the weighing date range, and everything that could not be resolved.

## Rules
- **Never set a spec quantity from the recipe alone.** The spec comes from the weighed plates, reconciled to the cost card. Where fewer than three plates were weighed, write the spec from what is there, set `spec_basis` accordingly, and put the dish in `not-weighed.csv`. Where no plate was weighed at all, leave `spec_quantity` empty. Never average a recipe into a weight.
- Every figure must trace to a supplied input file. Never fill a missing weight, plate cost, yield, tool capacity or portions-sold count with an estimate, a book yield, a typical figure or a web price. The gap goes in `not-weighed.csv`.
- **Never write a portion as an instruction without a tool.** Never write "a generous ladle", "a good handful", "a drizzle", "a scoop" or "to taste" into any output. A component with no tool in the supplied tool list reads `goes on the scales` in the `tool` column, and goes in `not-weighed.csv`.
- Name every tool by its number or capacity as it appears in the tool list, for example `number 16 scoop, levelled` or `60ml ladle`. Never describe a tool.
- **Never state, select or correct a legal measure for any drink.** Record the owner's stated house measure and the permitted quantities exactly as supplied. Where they do not match, write the question and stop. Do not write that a measure is wrong, permitted, required or unlawful.
- Never invent a tolerance. Tolerances come from the decisions supplied. Where none is supplied the cell is empty and the row goes in `not-weighed.csv`.
- Never claim a photograph that is not in the inputs. A spec sheet references a photograph only by a filename present in the folder, with the date read from the file or from the inputs. Where a photograph is missing, the sheet says `photograph not held` in that slot.
- Never change a spec quantity to make a plate cost hit a target, and never write a recommendation to cut a portion. Codex records weights and states arithmetic.
- Where the inputs show the business displays calorie figures, write one line on each spec sheet recording that the declared figure relates to a single portion and that the spec and the figure move together. Never calculate a kcal figure.
- Round weights to the whole gram or millilitre and money to two decimal places, at the point of display only. Line costs must sum to the plate cost at spec exactly.
- British English, £, DD Month YYYY dates. No em dashes. No emoji.
- Every output file carries, as its first line or its first row, the words: `Working document for the owner's environmental health officer, trading standards service or accountant to check before it is relied on. Not advice on weights and measures law, the premises licence, or calorie declaration.`

## Return
A list of the files written with their absolute paths and row counts, the number of dishes specced and how many are in the top ten, the number of dishes with three weighed plates and the number with fewer, the number of components with no tool, the number of components with no cost figure, the number of blind tests recorded and how many fell outside tolerance with what was changed, the number of spec sheets missing one or both photographs, and any drink line where the stated measure is not among the permitted quantities supplied.