1. Soybean juice is a unique food in Beijing. When grinding mung beans into vermicelli or dough, the starch is taken out and the remaining light green and blue soup is fermented and boiled. It is said that as early as the Qianlong period, bean juice had been introduced to the royal family. There is a saying in old Beijing that you can't be a real Beijinger without drinking bean juice. Because the smell and taste of soybean milk are unique, it is difficult to get used to it unless it is exposed for a long time.

2, drinking bean juice is exquisite, first of all, it must be very hot, and occasionally it is best to soak a few bubbles of hot air. In addition, it must be accompanied by finely cut shredded mustard, drenched with spicy oil, and at the same time, two "Yingbier", sweet and sour, salty, red and spicy, account for four of the five flavors, plus Yingbier's crisp fragrance, a perfect match!

3. Soybean juice has a long history. It is said that as early as Liao and Song Dynasties, it was a popular folk food. In the eighteenth year of Qianlong (1753), someone went to the temple to play the original name: "Recently, a new bean juice was sent to check whether it was clean and drinkable. If there is no clean one, recruit two or three bean juice makers and send them to the royal chef. " As a result, bean juice from the people became the royal meal of the court.

4, mung beans 1 kg, spicy pickles in moderation. Bean juice is actually the leftover of mung bean starch or vermicelli. Soak mung beans until they can be twisted and peeled, then take them out, grind them into fine pulp with water and pour them into vats for fermentation. Starch sinks to the bottom of the tank, and soybean juice floats on it. Fermented bean juice must be boiled with water in a big casserole, then boiled with fermented bean juice, and then kept warm with low fire, and served with food.

5. Screen mung bean impurities, wash them, put them in a pot and soak them in cold water (warm water is used in winter, and the water volume is twice as high as mung bean) for more than ten hours. When rubbing the bean skin by hand, take it out and add water to grind it into a thin paste (the finer it is, the better). The thin paste is about 2.65 kg per kg of mung beans. Then, add 1.5 kg of slurry water (that is, clear water skimmed from bean juice and starch before) to the dilute paste, and add not less than 12 kg of cold water for filtration, and about 17 kg of slurry and 2 kg of bean dregs can be filtered out.

6. Pour the slurry into a vat and let it settle overnight. White starch precipitates to the bottom of the vat, with a layer of grayish brown black powder on it, a layer of raw bean juice with grayish green color and sticky texture on the bottom, and floating foam and slurry on the top. Skim the froth and slurry, take out the raw soybean juice (about 8 kg raw soybean juice, about 500 g starch and a small amount of black powder), precipitate again before cooking, and precipitate for six hours in summer. It will precipitate all night in winter. After settling, skim off the mud on it.

7. Put a little cold water in the pot, bring it to a boil, and then pour in raw bean juice. When the bean juice gradually rises and overflows the pot, immediately switch to low fire to keep warm (high fire cannot be used at this time, otherwise it will turn into hemp tofu one by one), and eat it with spicy pickles.