Udon (饂飩, usually written as うどん) is a type of thick wheat flour noodle of Japanese cuisine.Udon is often served hot as a noodle soup in its simplest form, as kake udon, in a mildly flavoured broth called kakejiru, which is made of dashi, soy sauce (shōyu), and mirin. It is usually topped with thinly chopped scallions.