粉汤 is essentially a colloquial shortening of
粉丝汤 ('glass noodle soup'). Regional versions vary widely — mutton-and-mung-bean vermicelli in Ningxia and Gansu, seafood vermicelli in Shandong, pork-and-kelp vermicelli in the northeast — but the core is always translucent bean-starch or sweet-potato-starch vermicelli in a hot broth.
