Dong fen

Cellophane noodles, or fensi , sometimes called glass noodles, are a type of transparent noodle made from starch (such as mung bean starch, potato starch, sweet potato starch, tapioca, or canna starch) and water. A stabilizer such as chitosan (or alum, illegal in some jurisdictions) may also be used. They are generally sold in dried form, soaked to reconstitute, then used in soups, stir-fried dishes, or spring rolls. They are called "cellophane noodles" or "glass noodles" because of their cellophane- or glass-like transparency when cooked. Cellophane noodles should not be confused with rice vermicelli, which are made from rice and are white in color rather than clear (after cooking in water). Cellophane noodles are made from a variety of starches. In China, cellophane noodles are usually made of mung bean starch or sweet potato starch. Chinese varieties made from mung bean starch are called Chinese vermicelli, bean threads, or bean thread noodles. Chinese varieties made from sweet potato starch are called fentiao or hongshufen. Thicker Korean varieties made with sweet potato starch are called sweet potato noodles or dangmyeon.

Source: Wikipedia