The head, the bones and the trimmings left after the flesh has been taken off a salted mackerel. Those make the stock, daikon goes in, kelp broth is added, salt adjusts it, spring onion is scattered over, and the result is a clear soup.

Semba was the wholesale district at the centre of Osaka's commerce through the Meiji and Taisho years, and the merchant houses there kept a great many live-in apprentices. What those households ate was plain: tea over rice and pickles morning and evening, one soup and one dish at midday. Fish appeared on the table twice a month.

This soup is what was done with the remains of those two fish a month. Nothing thrown away, nothing bought, nothing that took long to prepare. In a house where everybody was working, all three of those conditions had to be met at once.

Fresh mackerel fillet is often used now, and vinegar or soy sauce is added at the end, and it is served in ordinary restaurants around the city as well as at home. The reason for building a soup out of offcuts has entirely gone. What survived is the name and the method — a piece of thrift kept up, in a city that has not needed to be thrifty in that particular way for a century.