Udon noodles made from flour and buckwheat noodles called soba are the most popular varieties of Japanese noodles. Udon noodles are made from wheat flour, which is mixed with salt and water into a lump of dough. After that the dough is rolled out so that it is thin and then it is cut into strips. Traditionally, thin and brown buckwheat noodles have been preferred in the eastern part of Japan, while thick and white udon noodles have been preferred in the western part of Japan. People eat udon both hot and cold. Chilled noodles dipped in cold broth are especially preferred during the hot and humid Japanese summers. Like soba, udon can be eaten simply in a broth garnished with small quantities of condiments such as scallions and red pepper. People often eat udon, however, with their favorite ingredients such as deep fried tofu (bean curd), prawn tempura, raw eggs, and slices of boiled fish paste called kamaboko. Many people also prefer to eat nabeyaki udon, which refers to udon noodles cooked with vegetables, meat, and broth in an earthenware dish. While nabeyaki udon is eaten all year round, it is especially popular during the winter.
In addition to udon there are several other kinds of noodles made from flour. These noodles mainly differ by their shape. Hiyamugi, which is served chilled, is thinner than udon and somen, which is also usually served chilled, is the thinnest of all. Kishimen, long and flat noodles, are also well-known. Kishimen is a specialty from Nagoya (in Aichi Prefecture).
Many Westerners may be offended when the Japanese slurp their noodles. This is quite proper, however, because it is necessary to eat the noodles quickly. Otherwise the noodles will get soft. In other words, slurping noodles is the way to eat noodles so that they do not lose their flavor. For this reason, it is not considered bad manners in Japan to make noise when eating noodles.