Sōmen , somyeon, or sùmiàn is a very thin noodle made of wheat flour, less than 1.3 mm in diameter. The noodles are used extensively in East Asian cuisines. Japanese sōmen is made by stretching the dough with vegetable oil, forming thin strands that are then air dried for later use. This is distinct from a similar thin noodle, hiyamugi, which is knife-cut.