Mince half the prawns and roughly chop the other half. Combine prawns with water chestnuts, spring onion, grated ginger, 2 tsp Shaoxing wine, 1 tsp soy sauce and tapioca starch. Mix well and set aside.
| Having two sizes of prawn will result in a slight bite when eating the har gao, instead of a mush
In a mixing bowl, add wheat starch and tapioca starch and pour in 1 cup boiling water. Mix well with chopsticks until you form a dough.
Knead the dough until springy, then divide in two and roll out into 1 inch sausages.
Using a rolling pin, roll out the dough. Use a 4 inch circle oiled cookie cutter to cut out circles.
| The oil on the cookie cutter ensures a clean cut, without dough sticking to the surface. If you do not have a cookie cutter, you may use a cup with a thin rim (ie paper cup) with a diameter of 4 inches.
Place ½ tbsp filling into the skin and pleat. Repeat for all.
Line a steaming basket with parchment paper. Steam the dumplings for 6 to 7 minutes, until the skin is translucent and the prawn filling is cooked.
Serve with chilli sauce on the side.