Mix the prawns, cabbage, sesame oil, soy sauce, ginger, and garlic in a bowl.
Place one teaspoon of filling onto a gyoza wrapper, wet the edges, and seal while pinching to create a fan shape.
Repeat the assembly process until all 30 dumplings are formed.
Heat vegetable oil in a large lidded pan and fry dumplings for 2 minutes until crisp.
Add 100ml of water to the pan while being careful of hot oil spits.
Cover the pan and steam the gyoza over reduced heat for 6 minutes until soft.
Mix soy sauce, sesame oil, and black rice vinegar to create a dipping sauce.
Serve gyoza garnished with spring onions and chilli with the sauce on the side.