Ishiru is the fish sauce of Noto. The name is said to be a worn-down form of uoshiru, fish liquid, and depending on the district it is also called ishiri or yoshiru.

The main raw material is squid viscera. In some places sardine, round herring, mackerel, or horse mackerel go in instead. Natural salt is added, the whole thing is packed down, and then it ferments and matures for several years. The proportions are not fixed, and every maker along this coast has their own.

Nobody is certain when this started. There is no settled account, though it is agreed that ishiru was being made by at least the 1700s. What comes out has a pronounced smell and a distinct character, with the flavor of everything that went into it dissolved into the liquid. The color is a dark amber, nothing like the clarity of soy sauce.

For the hotpot, seasonal fish and vegetables go into a pot with stock and ishiru and are simmered together. Use too much and it takes every other flavor in the pot along with it. There is also ishiru no kaiyaki, cooked in a scallop shell used as a vessel over the heat. Both are winter fixtures here. Something that took several years to make gets poured into a pot and eaten over the course of one evening.