Cut the root off the pak choi to separate the leaves. Place in a food processor with the spring onion and pulse until finely chopped. 

Add in the remaining filling ingredients, and pulse until everything is well combined

Place one of the wonton wrappers on a chopping board, one of the corners pointing upwards. Brush the top half of the square with a little water, then place a half teaspoon of the filling in the bottom corner

Roll the wonton upwards till you have a sausage shape. Press the wrapper firmly at each side of the pocket of filling. Bend the left side in, dab with a little water, then fol the right side over the top

Place the wonton on an oiled baking tray, and repeat until you have run out of wrappers. Put 12 of the wonton to one side, and then place the tray in the freezer for 1 hour. Once hardened, the wonton can be placed into a tub or freezer bags. Any leftover filling can be frozen for later

For the soup, place the chicken stock in a saucepan with the ginger and garlic paste. Turn on the heat and add the soy and sesame oil

Once the soup starts to boil, turn the heat to a simmer and add the onions and the wontons. Turn the heat down, and place a lid on the pan. Simmer for about 15 minutes

Serve with some steamed buns.