For the dipping sauce, pour the soy and vinegar into a small bowl and mix to combine. Add a pinch of the chilli powder and set aside. Note: The amounts given are for one serve, so if serving two or three people, just double or triple the recipe.
For the gyoza, toss the cabbage in a colander with 2 teaspoons of salt and leave to drain for 15 minutes. Squeeze the salted cabbage to drain excess liquid. Combine cabbage and all other gyoza ingredients, except for the skins and vegetable oil, in a large bowl and mix well with your hands or a spoon. You really want to mix this well to make sure the ingredients are well incorporated into the mince.
To assemble the gyoza, have everything ready to go! The room temperature gyoza skins, the filling, a plate or board lined with glad wrap so they don’t stick, and also a small bowl of water to help seal the gyoza.
Hold the gyoza skin in one hand and place a tablespoon of the mixture in the centre of the gyoza skin. Paint the entire edge of the gyoza skin with water and slightly envelope the mixture, as if you were holding a taco. Using both hands, pinch the gyoza edges together and make a small crimp. Continue all the way along until the gyoza is completely sealed. Repeat with remaining gyoza skins and mixture.
In a large, heavy based fry pan, heat the oil over a med-high heat and add the gyoza in a single layer, fairly tightly packed and flat side down. Cook until crispy and golden on the base of the gyoza (approx. 3 minutes). Add 200ml of water to the base of the pan and cover to steam the gyoza. Cook until the liquid has completely evaporated and the gyoza are cooked through. (approximately 7 minutes). Be careful when adding the water as it will bubble and spit as soon as it hits the hot oil.
Serve gyoza hot with the dipping sauce.