1) Wash the duck and put it in the pot. When the fire is over, skim off the foam and take it out for use.
2) Drain the water in the casserole and light the fire. Then add the onion, ginger, garlic, cumin, clove, pepper, star anise, cinnamon, Xiangye, liquorice and Xianggu mushroom. When the water boils, put the duck in.
3) Pour in the old soup, then add in some old soy sauce, sugar and salt. Cover and simmer for about 1 hour.
4) In another pot, put the stewed duck into the pot, then put in a little stewed duck soup, put some sugar in it, and collect the soup over medium heat.