Place a pan over a medium heat with a tbsp of olive oil. Add the chopped onion, celery, carrot, garlic and cook until soft. Add the beef mince, season, and cook until browned.
Add the tomatoes, wine, beef stock and a handful of chopped fresh basil. Allow to reduce for 10 minutes then remove from the heat and set to one side to cool.
To make the dipping sauce, cook the onions and garlic until soft, then add the chilli and tomato paste and cook for another minute. Add the whole tomatoes and break them up with a wooden spoon and cook for 10-15 minutes until the sauce thickens. Stir in the vinegar, a handful of chopped fresh basil and some seasoning. Set to one side.
With the gyoza skin in the palm of one hand, place 1/2 - 1 tsp of bolognese mixture into the centre of the wrapper and gently wet the top half with water.
Fold the gyoza skin in half, and pleat it with your finger and thumb, sealing it at the top. Place the finished gyoza onto a floured plate.
Heat olive oil in a pan and cook the gyoza, flat side down, until they are crispy on the bottom. Once crispy add a splash of beef stock to the pan to cover the bottom of the gyoza, place a lid on top and steam them until the stock has evaporated.