1. Prepare materials. Pork ribs, yam, minced garlic, flour, light soy sauce, dark soy sauce, oyster sauce, salt, sugar, pepper, starch, cooking oil.

2. Scrub the ribs with flour and rinse thoroughly.

3. After washing the ribs, add minced garlic, light soy sauce, dark soy sauce, oyster sauce, sugar, pepper, salt and starch and mix well.

4. Add some cooking oil, stir, and marinate for 40 minutes.

5. Peel the yam and cut it into sections, spread it on a plate, put the ribs on the yam, and pour the sauce in.

6. Place in a steamer or steamer and steam for 1 hour.

7. Finally, take it out of the pan and sprinkle with chopped green onion!