In a large bowl, combine pork, prawns, sugar, wine, soy sauce, ginger and a small handful of the chopped spring onions. Blend well, and let stand for 25 to 30 minutes.
Place about one teaspoon of the filling in the centre of each wonton wrapper. Moisten the edges of the wrapper with water, then pull the top corner down to the bottom, folding the wrapper over the filling to make a triangle. Press edges firmly to make a seal. Bring left and right corners together above the filling. Overlap the tips of these corners, moisten with water and press together. Continue until all wrappers are used.
To make the soup, bring the chicken stock to the boil. Drop wontons in, and cook for 5 minutes. Garnish with remaining chopped spring onion, and serve.
Uncooked wontons will keep in the freezer for two months if well wrapped. Thaw before frying, but they can be boiled straight from frozen and cooked 2 minutes longer.
For fried wontons
Heat 500 to 750ml of oil in a wok until hot. Fry wontons in batches until golden, 2 to 3 minutes on each side. Drain. Serve with plum sauce.