In a large bowl, mix the pork, prawns, spring onions, light soy sauce, shaoxing wine, sugar, salt, ginger, sesame oil and pepper with your hand. It will take a few minutes, but eventually, the mixture will become paste-like. Once you’re happy with the consistency, your siu mai filling is ready to wrap.
To see how I wrap my siu mai watch the video below. Keep a small bowl of water nearby. Add a heaped teaspoon to the middle of the wrapper and then roughly wrap the sides up against the filling, folding over as you go. Forming an O with your thumb and forefinger, push the wrapper through the O, forming a tight seal around the top of dumpling. Using a knife, push the filling to the edges and push down like you're pushing the filling in to a pocket. And then using some water, neaten the edges and push them down, all the while keeping the dumpling held tightly. Place the dumpling on a flat surface and push down to flatten the bottom so it will stand upright.
Put the dumplings in a steamer, lined with oiled greaseproof paper (see notes above for greaseproof paper method). In a large wok or pot, fill with 3 inches of boiling water and steam the siu mai over a high heat for around 8-10 minutes. Eat hot, and serve with soy and chilli sauce.