To clean the pig's stomach, turn it inside out and rub a handful of cornflour or tapioca flour together with 1-2 tablespoons of coarse salt on the stomach. Rub vigorously until it turns slimy. Rinse under running tap water until clean. Then use a knife to remove the sticky membrane. Blanch the pig's stomach in boiling water. Remove and trim away the fats. Rinse again until completely clean. Stuff the cavity with peppercorns, tong kwai and kei chi.
Blanch spare ribs and chicken feet in boiling water. Drain and set aside. Put the stomach, spare ribs, chicken feet and water into a double boiler pot and double boil for 2-2 ½ hours over a medium-low heat or cook in a slow cooker for 5-6 hours.
Just before serving, remove the pig's stomach and slice into bite-sized pieces. Add salt to taste.