1. Take a catty of soybeans one day in advance on sunny days and put them in clear water.

2. The next day, cook and cook. The longer the cooking time, the better. Pick up the drained water and let it cool completely.

3. After cooling, mix in half a catty of flour (raw), stir well, and basically take shape by hand. Spread on a bamboo piece or mat with air permeability at the bottom, with thick palms. Cover it with cotton wool or something, and cover it tightly and thickly. Then put it in the shade for fermentation.