Two Tai, Fifty Guests and a Nicked Yanagiba
A 50-guest kaiseki dinner on Saturday has a sashimi course of three tai slices at 14 g per guest, plus 15 g of ken and tsuma per plate. Two whole madai arrive on Friday: 2.9 kg and 3.4 kg round weight, head on. The kitchen's planning figure is 35% usable sashimi from whole tai. At 14:00 on Saturday the sashimi cook, three months into the job, reports that the 300 mm yanagiba has a 1.5 mm nick about 20 mm from the tip, caused by an earlier cook cutting a partially frozen block. On hand: one deba, one usuba, a 1000/3000/8000-grit stone set, no spare yanagiba, and 1.2 kg of daikon for katsuramuki. Service is at 18:00. The head chef says to just slice carefully and to use the usuba if needed.
1. Do the numbers: will the two tai cover 50 portions at the specified slice weight? Show the calculation and state the decision.
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Requirement: 50 guests × 3 slices × 14 g = 2,100 g of plated sashimi.
Supply at the planning yield: (2.9 + 3.4) kg × 0.35 = 6.3 kg × 0.35 = 2,205 g.
That leaves a margin of 105 g, about 5%. That is not a margin, it is a rounding error:
- Slice weight varies by at least ±1 g in normal hand-cutting, which is 50 × 3 × 1 g = 150 g of variance - larger than the whole buffer.
- 35% is an average across fish. The 2.9 kg fish will yield below it and the 3.4 kg fish above it, so the real number is less predictable than the arithmetic suggests.
- Any trimming of a bruise, a blood line or a soft spot comes straight out of the buffer.
Decision: the two fish are not sufficient for a plated course at 14 g. Either bring in a third tai of about 2.5–3 kg, or cut the slice to 12 g (1,800 g, an 18% margin) and add a second garnish component so the plate does not read as reduced. Do not plan to 100% of a yield estimate on a banquet course.
Separately: 50 × 15 g = 750 g of tsuma; 1.2 kg of daikon at roughly 80% usable after trimming gives about 960 g, so the garnish is covered.
2. Set out the knife plan for the afternoon: which knife for which task, and what you do about the 1.5 mm nick before 18:00.
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Knife selection by task.
- Deba for the fish: it is a stout single-bevel blade with a thick spine, made for taking off a head behind the pectoral fin, opening the belly, running along the spine and lifting the fillet away. Using a yanagiba here is how blades get broken.
- Yanagiba for slicing: long, thin, single-bevel, so the slice is taken in one drawing stroke from heel to tip without sawing.
- Usuba for the daikon: katsuramuki and ken are vegetable work on a straight-edged vegetable blade.
The nick. A 1.5 mm nick means the entire edge must come back about 1.5 mm to reach sound steel. Start on the 1000-grit at the existing bevel angle - do not raise the angle to save time - and grind until the nick is gone, checking with a marker line. Then refine on 3000 and finish on 8000. This is 60–90 minutes of correct work, so it starts at 14:05, not at 17:30, and it is assigned to the strongest sharpener on the team, not to the cook who damaged it.
Sequencing. Fillet both fish with the deba first, wrap and hold at ≤4°C, and cut the daikon while the yanagiba is being repaired. If the nick is still visible at 16:30, source a replacement blade - a borrowed yanagiba or a sujihiki - rather than going into service with a damaged edge.
A chipped edge tears cells instead of cutting them. The surface goes ragged and oxidises, the slice weight becomes inconsistent, and the plate looks tired even if the fish is perfect.
3. The head chef says the usuba can slice sashimi if the yanagiba is not ready. Evaluate that instruction.
Read the worked answer
I would not follow it, and I would say so before 17:00 rather than at the pass.
The usuba is a single-bevel vegetable knife. Its edge is thin and straight, its bevel geometry is set for cutting firm plant tissue, and it has no length for a drawing cut. Slicing 2 kg of fish through skin, connective tissue and the fine pin bones near the tail will roll or chip that edge, and the straight profile tends to crush and drag rather than slice cleanly. The likely outcomes are a damaged usuba, torn sashimi and an inconsistent portion - three problems instead of one.
If the yanagiba genuinely cannot be made ready, the correct fallbacks are: a sujihiki or a long, sharp double-bevel slicer; a very sharp deba used only for rough portioning, with the final presentation slice taken by the strongest cutter; or a change to a non-sashimi presentation for part of the course. What is not acceptable is a damaged yanagiba or a borrowed vegetable knife.
This is also a training point. A cook three months in should be told why the usuba is wrong, not just that it is wrong, and the knife-damage report should be logged so the frozen-block shortcut stops recurring.