First of all, we should choose plump soybeans as raw materials. After soaking the beans in water, we should cook them in a pot, empty the soup, put them in a clean pottery basin, cover them with fine gauze, and cover them with quilts or cotton-padded clothes on a hot kang. After more than ten days, a layer of white mucous membrane (long hair as you said) grows on the surface of soybeans, accompanied by salt, pepper and cotton-padded clothes. You can eat it after a few days. You'd better cook it again before eating.