1. Slice the green onion and ginger, peel the yam and cut into sections, soak the dendrobium and lotus seeds in water.
2. Cut the old duck into pieces and put it in a pot of boiling water, blanch the blood.
3. Remove the duck pieces and put them in the pot, add a little oil and fry to dry the water.
4. Add water to the pot, simmer for 20 minutes on a low heat; then add the coix seed and dendrobium, and simmer for 40 minutes.
5. Then add yam, ginger, green onions, and lotus seeds, and continue to simmer for 40 minutes.
6. Add appropriate amount of salt to taste before serving, and a healthy and fragrant "Dendrobium Duck Soup" is done.