Wash and peel the potatoes, and grind them into paste with a squeegee (a special tool for grinding potatoes). Because the ground potato paste will be oxidized to red when exposed to air, wash it with water for several times, put more water in the pot where the potato paste is placed, let it stand aside, and then pour out the water until the potato paste settles down. Repeatedly, the water gradually turns white, then filter it with a cage cloth, squeeze it out and put it in a small pot. Add salt, pepper noodles and aniseed noodles, mix them together, knead them into small balls and steam them in a steamer for about 20 minutes. The steamed leng is dark gray, elastic and tough, which is the most authentic leng-closing principle. Some people take the trouble to mix some flour or starch, so that the color is whiter and the taste is not as good as the previous method. Seasoning is also very important. It is best to stir-fry tomato sauce at home. If you like spicy food, add some dried peppers and oil the seasoning, which will be more delicious.