bonito (katsuo), sashimi grade

Katsuo is skipjack tuna, a small relative of the larger tunas and the same fish used to make katsuobushi flakes; sashimi grade means it is fresh, cleanly handled and intended to be eaten raw. The flesh is dark red, tender yet firm, and tastes noticeably stronger and more bloody than tuna, which is why in Japan it is often eaten with ginger, garlic, spring onion and a tart sauce, or briefly seared on the outside as tataki. Because it loses quality quickly, it usually reaches Europe and North America frozen, as a loin block or already seared. Look for it in the freezer section of larger Asian grocers, at Japanese fishmongers, or from mail-order suppliers that ship frozen. Watch the labelling: the name bonito is also used for Atlantic bonito, a different fish with paler, milder flesh.