cooking starch residue

Ma tofu is a special snack of Naiman Han nationality and a civilian food. This thing comes from the powder room in old Beijing. The powder room used to be the place where starch was produced. Put the beans on a stone mill and grind them with water. At the same time, the beans are divided into three things. The top thin became soybean milk, which is genuine and used to make starch; The top thin became juice, that is, bean juice; In the middle, a thick layer of stagnant dark green powder slurry is put into a cloth bag, heated and boiled, and the water is filtered out, which is sesame tofu.
Reprinted with attribution： https://cnlocality.com/(Chinese Specialty Products)