In a large mixing bowl, combine the beef mince, spring onion, ginger, ground Sichuan peppercorns, light soy sauce, Shaoxing cooking wine, white pepper, sesame oil, water, chicken bouillon powder and cornflour. Using chopsticks or gloved hands, mix thoroughly in one direction until the filling becomes sticky and slightly paste-like.
Place a gow gee wrapper in the palm of your hand and spoon about 1 to 1½ teaspoons of filling into the centre. Lightly wet the edge of the wrapper with water, then fold and seal. Continue until all of the filling has been used.
Heat 1 tablespoon of neutral oil in a large non-stick frying pan over medium heat. Arrange 10-12 dumplings in a single layer (they can be cooked straight from frozen) and cook for 5-6 minutes, or until the bases are golden brown.
Add 2-3 tablespoons of water to the pan and immediately cover with a lid. Reduce the heat slightly and steam for 5-7 minutes, or until the wrappers are soft and the filling is cooked through.
Remove the lid and cook for a further 1-2 minutes until most of the remaining water has evaporated and the bases are crisp again. Serve immediately with sliced spring onion, chilli oil, soy sauce and Chinese black vinegar.