Douzhi and Jiaoquan
Beijing has a long history of making mung bean milk. As early as in the Liao (907-1125) and Song (960-1279) dynasties, mung bean milk was very popular. Local people of Beijing love to drink mung bean milk, because it is rich in protein, vitamin C and rough fiber and helps drive away summer heat, invigorate the function of the spleen and whet the appetite.
It is a dish from Beijing cuisine. It is similar to soy milk, but made from mung beans. It is a by-product of cellophane noodle production. It is generally slightly sour, with an egg-like smell.
Fermented green bean juice (douzhi) is the boiled juice left over after the process of making bean curd and then fermented. With a sour taste and fermented smell, it takes a few tries to get used to. The juice is normally drunk along with pickled turnip slices (xiancai), and a fried flour loop (jiaoquan).