Edo Tuna and Leek Hot Pot (ねぎま鍋, Negima Nabe)

Fatty tuna makes people nervous now because it sounds precious. Negima nabe began with the opposite feeling. Toro was once the troublesome part, too soft and rich to keep well, and the Edo answer was sensible: put it in a pot with negi and let the fat season the broth.

The one detail that decides this dish is restraint. Grill the negi first until the outside blisters and the inside softens, because that little char gives sweetness and keeps the leek from tasting raw in the pot. Then simmer the broth, not the tuna. Slip the pieces in at the end and pull them while the center is still tender. Boil them hard and you've paid good money to make dry fish. A small crime, but still a crime.

This is nabemono, the shared pot, and it belongs to cold weather when long Japanese leek is sweet and tuna carries good fat. The seasoning is plain: dashi, shōyu, mirin, and sake. Nothing hidden. If the tuna is glistening fresh, the broth will become round as it cooks. If it isn't, change the dish. Sourcing first, always.