Pollock roe is steeped in a liquid seasoned with chilli. Left for days, the heat works inward through the membrane rather than sitting on the surface. Cut across, the sac shows tens of thousands of grains packed tight, and the texture of eating it is closer to caviar than to anything cooked.

In the autumn of 1948 a small grocery opened in Nakasu, in the middle of Hakata. The owner had spent part of his childhood in Busan and had never forgotten a chilli-cured cod roe eaten there. He began selling his version on the tenth of January the following year, the day of the Ebisu festival, when shops here pray for trade. It was, by the account his family tells, declared too hot by a customer on the second day.

He spent about ten years adjusting it, changing the chilli, the salt and the time, until it suited people who had not grown up with it. Then, instead of patenting the method, he gave it to anyone in the city who asked. People around him urged him to protect it; he declined, repeatedly, and the reasons he gave were not commercial.

That is why Fukuoka has so many makers rather than one. By refusing to keep it, he made it belong to the place rather than to himself, which is a harder thing to do than it sounds.