Sushi

The defining ingredient of sushi is not fish but rice — specifically, vinegared rice. The word refers to the seasoned rice itself, which is why there are so many forms of sushi that contain no raw fish at all.

Its distant ancestor was a preservation technique. Fish was packed in salt and cooked rice and left to ferment for months; the souring rice protected the flesh, and the rice was usually discarded before eating. Versions of this method spread through rice-growing regions of Asia, and a fermented style still survives in parts of Japan, where it is prized for its powerful, cheese-like pungency.

Over centuries the fermentation grew shorter and the rice went from packing material to part of the meal. Once cooks learned to imitate the sour flavour by seasoning rice with vinegar, the long wait became unnecessary and sushi turned into something that could be made and eaten the same day.

The style most people picture today — a hand-pressed finger of rice with a slice of seafood laid across it — emerged in Edo, the city that became Tokyo, in the early nineteenth century. It was street food: quick, portable, sold from stalls to a hungry urban population, and closer in spirit to a modern sandwich shop than to fine dining.

Because there was no refrigeration, the fish was rarely raw in the modern sense. It was marinated in soy, salted, or lightly cooked, and the resulting flavours were assertive. Chilled transport and refrigeration in the twentieth century made pristine raw fish practical, and sushi shifted toward the clean, delicate presentation now associated with it.

A traditional sushi chef trains for years, and much of that training is about rice: its variety, how it is washed and cooked, the balance of vinegar, salt and sugar, and the temperature at which it is served, ideally close to body temperature so it contrasts with cool fish.

The family is broad. Nigiri is the pressed style; maki is rolled in seaweed; temaki is a hand-rolled cone; chirashi scatters toppings over a bowl of rice; inari is rice stuffed into sweet fried tofu pouches. Regional traditions add many more, including pressed box sushi from the Osaka area, which predates the Edo style.

Sushi travelled with Japanese emigration and then far beyond it, picking up local ingredients as it went — avocado, mayonnaise, cream cheese and deep-fried rolls are largely inventions of overseas kitchens. Purists and innovators have argued about this for decades, which is itself a sign of how thoroughly the dish has been adopted worldwide.