Tentsuyu is commonly known as Japanese tempura dipping sauce, but much the same broth or soup is used widely in Japanese cuisine as a general-purpose dipping and simmering sauce (but under other names).
The recipe for tentsuyu depends on the seasons and on the ingredients for which tentsuyu is being prepared. A general, all-purpose, tentsuyu usually consists of three parts dashi, one part mirin, and one part shoyu (Japanese soy sauce). For ingredients with strong odors or flavors, however, sake and sugar might be used instead of mirin, or more or less shoyu might be used.
A mostly identical broth is called donburi ni shiru ("donburi simmering soup") when used to simmer the ingredients for donburi. This broth is also used as a hot soup for dishes like agedashi tofu (deep-fried tofu in broth).
