Bluefin
Draft. Written from the catalogue and shipment notes; not yet fact-checked by James or Tony. Do not publish until it is.
What it is
Honmaguro (本鮪) is Pacific bluefin, Thunnus orientalis. At Toyosu it is sold by the tuna brokers, who buy whole fish at the morning auction and break them down for restaurants. Omakon buys from the broker, not the auction, which is how a Vancouver kitchen gets a 20 oz block instead of a 200 kg fish.
Wild fish are caught around Japan; “ranched” fish are wild-caught young and grown out in pens in Kyushu and Shikoku. Both are honmaguro. Ranched is more consistent in fat; wild varies more and peaks in winter.
The three cuts
| Cut | Japanese | Where on the fish | Fat | Use |
|---|---|---|---|---|
| Akami | 赤身 | The lean back and inner loin | Low | Nigiri, zuke (soy-marinated), poke, tartare. The cut Japanese chefs judge a tuna by. |
| Chu-toro | 中トロ | Between belly and back, upper belly | Medium, marbled | The all-rounder for nigiri and sashimi. |
| O-toro | 大トロ | The belly, especially the front (kama-toro, jabara) | High | Rich, melts; one or two pieces per guest. Torched aburi, or raw. |
Negitoro is scraped tuna from around the bones and skin, sold by weight; nothing to do with a cut.
What a saku is
A saku (柵) is a rectangular block cut with the grain, trimmed, ready to slice. Omakon’s retail saku run about 20 oz; wholesale accounts can take full loins or quarter loins. A saku is priced by weight, so the final charge follows the packed weight.
Slicing
- Work cold: fish from the fridge, a clean wet board, the longest sharp knife you own.
- Look at the grain lines (sinew). Slice across them, one pull per slice, no sawing. For nigiri, 2 to 3 mm; for sashimi, 6 to 8 mm.
- O-toro has thick sinew; slice thinner, or score across it, or torch it. Akami sinew is thin and eats fine.
- Rest akami 15 minutes out of the fridge before serving; it tastes of more. Serve toro colder.
Storing
- Unopened saku: 0 to 2 °C, best within 2 days of landing, acceptable to 3 for akami.
- Opened: wrap tight in paper towel then film, change the towel daily. Bloodline edges darken first; trim, do not discard.
- Super-frozen (-60 °C) bluefin is a separate product: thaw in salted ice water or overnight in the fridge, never at room temperature. Once thawed, treat as fresh and use within 2 days.
- Zuke: akami in soy, mirin and sake for 20 to 40 minutes buys a day and adds flavour.
See the current selection · Related: Bluefin tuna, the ultimate guide in the Journal.