250g pork char siu with fat (store-bought char siu), diced
1 onion, diced
2 tbsp frozen green peas, thawed
A little Shao Xing wine
1 tbsp light soy sauce
1 tbsp oyster sauce
3/4 tsp pepper
1/2 tbsp thick soy sauce
1/2 tsp salt or to taste
2 tbsp castor sugar
1/2 tsp sesame oil
2 tbsp water
1 tsp cornflour
1 tbsp water
1 egg, lightly beaten
To prepare filling: Heat 2 tablespoons oil in a nonstick saucepan and fry onion until fragrant. Add char siu and sprinkle in Shao Xing wine. Toss and fry well. Add in remaining seasoning ingredients. Fry until filling is fairly dry. Drizzle in a little thickening and continue to fry for a while. Dish out and leave to cool completely or preferably chill in the refrigerator before use.
To prepare water dough: Combine all ingredients in a mixing bowl. Knead until soft and smooth. Leave aside for 10 minutes.
For the oil dough: Combine flour and shortening into a smooth dough. Leave aside for 10 minutes.
Divide oil and water dough into equal portions of 20g each. Wrap each piece of water dough with a piece of oil dough in the centre. Form into a ball then roll out into an oblong shape. Roll up Swiss Roll-style. Roll out into a thin round. Wrap a tablespoon of prepared filling in the centre. Pleat the edge into a Siu Pau shape.
Arrange each Siu Pau into a paper cup and brush with glaze. Bake in preheated oven at 180°C for 20-25 minutes or until golden or done. Serve warm.