In Hinase, on the southeastern edge of Okayama, fishermen began making this sometime in the middle of the Meiji era. It was the sushi for a day of celebration: a good catch landed, a prayer for safe boats. Spanish mackerel came off the deck and went straight onto vinegared rice. Nothing else was mixed in. The fish was the whole point.

Off to the side of the plate, or in a small dish next to it, sat some koko, the old winter pickle made from daikon salted down in autumn. It was there the way pickles are always there, as punctuation rather than content. At some point it stopped staying in its dish. Slices found their way into the rice, and whoever tasted the result decided it was better that way.

So the recipe changed by accident and stayed changed. That detail pleased me more than it probably should have. Most traditional dishes come with a story about someone deciding something. This one has a story about something spilling and nobody putting it back.

Now the rice is seasoned with the vinegar the mackerel was cured in, then folded with shredded pickle and green peas. The cured fish goes on top with a scattering of young sansho leaves. It is made without fail for the iris festival in May, for local festivals, and on the day a new boat is launched.