1. Peel, rinse and slice ginger.
2. Rinse and blanch old hen in boiling water for 1 minute so as to drain the fat and blood; Remove and immediately rinse in running water; Pat dry.
3. Add all ingredients and pour 6L water into a large pot; Bring to the boil over a high heat; Keep on boiling for a while; Skim off the foam and blood clots on the surface; Simmer over a low heat for 5 hours.
4. Turn off the heat; Skim off the grease on the surface; Strain the stock through a sieve; Flavor with se