1. Wash soybeans and soak them in clear water for more than 1 hour.
2. Wash the trotters and cut them into pieces, then soak them in water.
3. Take out the trotters and drain them, then put them in a pot and cook for 5 minutes.
4. After 5 minutes, remove the trotters and rinse them with running water.
5. Put the pig's trotters in the casserole, then add the soybeans, onions and ginger.
6. Pour enough water at a time.
7. Put the casserole on the fire and cover it. After the fire boils, turn to low heat 1.5-2 hours.
8. Season with salt before cooking, and then sprinkle with medlar.