You can buy these at a warehouse store, frozen. Of course they are not as good as the real thing. So here is the recipe I like. I typically make the filling the day before I actually assemble them, that way I don't feel like I am in the kitchen that long making these. My kids love these too.

Gyoza

1 lb. country style pork sausage
1 lb. lean ground pork
1 T. Japanese-style soy sauce
2 t. chili oil
1 carrot finely shredded
4 cloves garlic, minced
6 green onions chopped
2-3 T. fresh ginger, grated
1/2 med. fresh cabbage, shredded and chopped
1/2 c. beef broth
2 pkgs. round gyoza skins (produce section of store)
gyoza sauce (posted before)

In a large wok or skillet, break up sausage and ground pork. Saute this mixture over med-high heat, adding the soy sauce and chili oil. When the meat is browned, add the next 4 ingredients and stir fry several minutes. Add the cabbage and continue to stir fry until the cabbage is wilted. Add the beef broth, cover and let this mixture steam until most of the liquid is reduced. Remove the mixture with a slotted spoon and place in a bowl to cool. Using a gyoza press ( available in most oriental and department stores), place a single skin, centered on the press, moisten the edges with a couple of drops of water, then place about a teaspoon of the filling in the center, then squeeze the press closed. Heat a small amount - less than 1/4 cup of peanut oil in a large skillet over a med-heat. Place a dozen or so of the gyoza in the skillet and brown lighlty on both sides. Carefully add a 1/4 cup of water to the hot pan, quickly cover and let steam until the liquid has evaporated. Remove to cool on a wire rack or serve immediately, with dipping suce. Makes about 100. These freeze well.