There is no pan. A scallop shell is the pan. Nets dragged along the seabed brought up scallops that had been down there five or ten years, and their shells were the width of two hands, wide enough to set straight onto the fire with a portion of broth sitting in them. People were eating this in the Edo period.

The first versions were a fisherman's meal: a piece of sardine or mackerel with homemade miso spread over it, cooked in the shell over a fire on the shore. Now you melt miso into broth in the shell, add whatever there is to add, and finish by pouring in beaten egg and letting it set softly across the surface. In Tsugaru it is usually kept simple — egg and miso and not much besides. Down on the Shimokita peninsula they say the two halves of the name the other way round.

When eggs were still expensive, this was food for the sick and for women who had just given birth. One shell of hot, salty, fortifying broth was the whole of the treatment. Dazai Osamu put it into the book he wrote about walking through this province, which is how a good many people outside the region first heard of it.

Now it arrives late in the evening beside a glass of something cold, a small hot thing to keep a conversation going. The method has not changed at all. What the dish is for has changed completely, and nobody at the counter seems troubled by that.