1. Wash the bean skin, fold it in half along the length, cut it into strips about 1.5cm wide, and fold each three strips together, ready to knot.
2. Be careful when tying the knot. The bean skin without frying is fragile. After all, put them in the pan and fry them on both sides.
3. There is not much oil in the pot, just a thin layer. Scoop three to four tablespoons of old marinade. If not enough, add some water and salt. The soup will reach about two-thirds of the soybean skin
4. When the heat is high, cook in low heat for about 15 minutes. Turn it twice or three times in the middle to make it taste more even. At last, the juice can be collected in high fire.