Tuna sushi

Use sushi rice and tuna sold by a fishmonger for eating raw. Shape small portions of cooled rice into ovals, then lay thin slices of tuna over them; keep the fish chilled while you work.

Not automatically. “Sushi-grade” is not a regulated guarantee, so ask the fishmonger whether the tuna has had the freezing treatment needed to control parasites when fish is eaten raw; otherwise cook it.

It is best eaten soon after it is made, especially when it contains raw tuna. For homemade sushi, cool the rice quickly and refrigerate it within an hour; the Food Standards Agency advises keeping cooked rice for no more than one day.

Serve it with soy sauce, wasabi and pickled ginger, plus miso soup or a simple cucumber salad for a fuller meal. Dip the fish side lightly in soy sauce so the rice does not soak it up and fall apart.

Tuna sushi usually means a slice of tuna on a small mound of rice; tuna maki is rice and tuna rolled in nori and sliced. Tuna maki has 109 kcal per 100 g, compared with 156 kcal for tuna sushi.

Yes. Use salmon prepared for eating raw and make it as nigiri or roll it with rice and nori; cooked prawns or cucumber are useful alternatives if you do not want raw fish.

No. Tuna sushi pairs the fish with vinegared rice, while sashimi is sliced fish served without rice. Tuna sashimi has 24 g of protein per 100 g, compared with 7.2 g in tuna sushi.