Only when the acidity of the sour water reaches a certain requirement can it be ordered into tofu. The production of bean curd with sour sauce goes through eight basic processes, such as selecting materials to soak beans, grinding, defoaming, hanging bags to remove slag, boiling, cooking, secondary heating and pressing. Among them, the sour sauce used for cooking is similar to steaming steamed bread with flour as a starter, and the sour sauce is left once for making tofu. In the whole process, the local sweet mountain spring water was used to make tofu, and the slurry from the boiling process was put in a special tank, which turned sour by the fermentation of its own lactic acid bacteria, that is, "sour slurry", and then the tofu was made with the sour slurry.