1. Add the pork shoulder, salt, and sugar to a large bowl and knead with your hands until the meat becomes sticky, this should take about 7 minutes
2. To speed up the process you can use a food processor or an electric mixer
3. Add prawns and continue to knead for 4 minutes, the mixture should be sticky enough to form a ball
4. Add the pork lard and potato starch, and knead until combined
5. Add the white pepper, Yumyum, chicken bouillion powder, Shaoxing wine, sesame oil, mushroom and scallops and knead for another 3 minutes
6. Cover the mixture with cling wrap and let it chill overnight

To Assemble

1. Remove the chilled filling from the fridge
2. Use a rolling pin to slightly flatten your wonton wrappers, making the skin slightly bigger
3. Using a knife cut the wonton skins into an octagon
4. Take a wonton wrapper and place 1 tbsp of filling in the center
5. Form an “O” shape with your thumb and first finger
6. Place the wonton wrapper with filling in the center of the ring and use a fork to slowly push the filling into the “O”
7. The sides of the wrapper will naturally fold upwards to form that siu mai shape
8. Flatten the top of the siu mai with the butter knife and place it on a tray lined with baking paper
9. Repeat for the rest of the filling and skins, you should make 20 siu mai
10. Meanwhile, line a steamer with a circle of baking paper, make sure there are holes cut in the baking paper to prevent condensation and the siu mai sticking
11. Heat a large pot or wok filled halfway with water
12. Place your desired amount of siu mai in the steamer and steam for 10-12 minutes
13. Store any leftover siu mai in an airtight container in the freezer for up to 2 weeks