Thoroughly mix all ingredients for filling – yam, water chestnuts, prawns, pork mince, oyster sauce, Shaoxing wine, white sesame oil, ground white pepper, water, cornflour, five-spice powder. Stir, in one direction only, till mixture is sticky, about 3-4 minutes.
350 g fatty pork mince, 1 tbsp oyster sauce, 1 tbsp Shao Xing wine, ½ tbsp white sesame oil, ¼ tsp ground white pepper, 2 tbsp water, ½ tsp cornflour, ⅔ tsp five-spice powder