Extended information fans are one of the common foods in China. It is a kind of filamentous food made of mung bean and sweet potato starch, so it is named vermicelli. Often called vermicelli and winter noodles (mainly in Taiwan Province province), Korean peninsula is called noodle soup, and Vietnamese noodles are called noodles.
The best vermicelli is made of mung bean, corn starch or sweet potato starch, but the quality is not as good as mung bean vermicelli, because mung bean has the most amylose, which is not easy to rot when cooked and tastes the most greasy. Like spaghetti, it's dried and then sold. You'd better soak it in water to soften it before eating. The diameter of vermicelli is generally about 0.5 mm.
References:
Baidu encyclopedia-fans