1. An old duck weighing about 2 kg, sliced with ginger.
2. Peel the yam, cut it into large pieces with a hob, and wash it for later use.
3. A packet of Mao Ge old duck soup.
4. Boil a pot of boiling water and add the old duck until it is cut off.
5. Pick up the duck and pour out the boiling water.
6. Change another pot of water and add the old duck, ginger and Mao Ge old duck soup.
7. Cover the high-pressure pot cover and simmer for 20 minutes after the fire.
8. Steam, open the lid, add yam, cover the lid again, and simmer for 10 minute after boiling over high fire.
9. Put it in a soup bowl and a pot of fragrant old duck soup will be ready.