Mallard arrive on the lake from Siberia as the winter comes in. The flight is long, so the flesh is tight, and the birds have laid on fat to get through the cold. A duck that has just crossed a continent is better eating than one that has not, which is not an obvious thing, and the whole dish rests on it.

They go into the pot with leek, tofu and Chinese cabbage, in a first-draw stock of kelp and bonito and nothing more assertive than that. The duck fat surfaces and settles on the leek, and there are always people at the table taking the leek before the meat.

The season runs from November to March, because that is the only period when the shooting is permitted. Ask for it in summer and there is nothing to serve you; outside those five months the dish simply does not exist.

In the Edo period the mallard of the northern lake shore was a designated local product, sent up to the shogunate as tribute. Hunting on the lake itself is now prohibited, so the birds come from elsewhere. A dish that belongs to this shoreline is made from ducks that arrived from somewhere else, cooked in a place whose own water is closed to the hunters. Both halves of it come in from outside.