1. Wash the keel bones, boil them in cold water, then take out the keel bones and set aside;

2. Wash the lotus roots and cut them into large pieces;

3. Wash the red beans and set aside;

4. Take out the keel, put it in a casserole, add cold water and boil over high heat;

5. After boiling, add an appropriate amount of vinegar, then add the reserved lotus root pieces and Red beans, then boil together;

6. After boiling, simmer over low heat;

7. Boil for about 2 hours, add appropriate amount of salt to taste, and the soup is ready .