Preparation materials: ribs: appropriate amount, yam: appropriate amount, salt: appropriate amount, ginger slices: appropriate amount, pepper: appropriate amount, coriander: appropriate amount.

1. Cut the ribs into pieces, and then wash them with clear water.

2. Peel the yam, then wash it with clear water and cut it into pieces.

3. Add ribs, water, ginger slices and pepper to the pot and bring to a boil. Then skim off the foam and turn to low heat. Cover and cook for about 1 hour.

4. Boil the pot, add the yam pieces, and cook for about 20 minutes. The yam becomes soft. Sprinkle some salt and coriander before cooking.

5. done.