1. Pick up the sand and sundries of mung beans and wash them clean. Add 45 kilograms of water to the pot, pour in mung beans, add alum, cook over medium heat until the mung bean skin cracks, and take out the floating bean skin with a small colander.
2. When the mung bean is cooked until it blooms, put the washed millet into the pot, boil it with high fire, then simmer it with low fire. When it is half cooked, cook it with a spoon until the rice soup is thick and the beans and rice are uniform.