2. Wash the old duck, cut off its tail, cut it into small pieces, blanch it in a pot to remove the blood, and then take it out.
3. Soak Cordyceps sinensis, red dates and yam in water, and cut ginger into pieces.
4. Put all the ingredients into the pot, add enough water, bring to a boil with high fire, then turn to low fire for 2 hours, and finally add salt to taste.