Hot and sour noodles originated in western Sichuan and are named after their hot and sour taste. They are a traditional snack in Sichuan, Chongqing, Guizhou and other places. Hot and sour vermicelli is made from sweet potatoes, peas, and red sweet potatoes.
Because the tastes vary from place to place, the vermicelli made is also different. In the south, rice noodles are used, while in the north, vermicelli is used.
There are two types of sweet potato vermicelli in hot and sour noodles, one is "water vermicelli" and the other is "dry vermicelli". "Water powder" is ready-to-use sweet potato starch made with a colander, and "dry powder" is processed dry vermicelli. For convenience and simplicity, the hot and sour noodles on the market all use dry vermicelli.