Chop cabbage fine, place in colander and pour boiling water over the cabbage. Cool to touch, then squeeze cabbage well to get the water out. In a bowl mix cabbage, chopped green onions, chopped mushrooms and grated ginger.
Mix ground beef, wine, soy sauce, sesame oil and black pepper together with vegetables; mix well.
Place a small amount of filling (about 1 teaspoon) in center of gyoza wrapping and fold in half. Pleat edge to seal. If edges won't stick together, dampen the inside edge with a little water, then pleat. Put 2 tablespoon salad oil in Then, at edge of pan, pour in a little water, up to 1/4 of the depth of the pot-stickers. Cover, turn heat to low and simmer until water is gone.
Mix soy sauce with chili sesame oil. Use a proportion of 10 parts soy sauce to 1 part oil; if you use a 5 to 1 proportion it may be a little hot for most people. The authentic sauce is a 2 to 1 proportion.
