The Japanese thick wheat noodle often served in a hot broth is udon.
Udon is made from wheat flour, water, and salt, producing a thick, smooth noodle with a pleasantly chewy texture. It is commonly served in dashi-based broth seasoned with soy sauce and mirin, often with scallions, tempura, fish cake, or fried tofu.
Udon has many regional styles. Sanuki udon from Kagawa Prefecture is especially famous for its square shape and firm bite. The noodles may also be served cold with a dipping sauce, stir-fried, or cooked in curry sauce, so hot broth is common but not required.
A frequent mix-up is soba, which is generally made from buckwheat and is thinner. Sōmen is also a wheat noodle, but it is much thinner and is usually served chilled. Ramen differs in both ingredients and preparation, typically using alkaline wheat noodles and a more intensely flavored soup.