Tororo Konbu

Kelp softened in vinegar is layered many sheets deep, pressed, then shaved thin off the side — that is the basic processing. It is light and fluffy, carrying a tangy savoriness from the vinegar cure. Shaving the dark outer layer yields "black tororo," while the pale center yields "white tororo" — a shift in where the blade cuts changing both taste and look entirely.

Kelp softened in vinegar is stacked into a thick block and shaved thin off its side like a plane, the standard way to make tororo kelp. A closely related product, oboro kelp, instead planes a single sheet of kelp directly rather than stacking several — the distinction between stacking-then-shaving and shaving-one-sheet is what gives each its own name and texture.

During the Edo period, Kitamaebune ships ran what came to be called the "kelp road," carrying Hokkaido kelp to ports along the way, where industries for curing and processing it are said to have taken root. Tsuruga was one such port, and this craft of softening thick kelp in vinegar and shaving it thin is said to have developed there as a way to make it both long-lasting and easy to eat — what those ships carried was not just kelp itself, but the craft of processing it.