Make the pork filling: In a large bowl combine the ground pork, cabbage, green onions, ginger, garlic powder, salt, pepper, soy sauce, vinegar and sesame oil.
Fill the wontons: Take a wonton wrapper and lay it out flat onto a hard surface lined with parchment paper. Using your finger, rub warm water onto the edges of the wonton wrapper. Place a tablespoon of the pork mixture into the center of the wonton. Take one corner and pull the opposite corner up and pinch them together. Starting from the top, pinch the sides together until the wonton is sealed.
Cook on the stovetop: Spray the bottom of a non-stick skillet with cooking spray. Place the potstickers, flat side down into the skillet and turn the heat to medium-high heat. Once the pan starts to heat up, pour ½ cup of water into the bottom of the pan and cover with a lid. Cook the potstickers for 8 minutes. Remove the cover and continue to cook the potstickers until the water is completely evaporated and the bottoms are golden brown. (Keep an eye on the heat to make sure they do not burn on the bottom and do not move them at all during this time.)
Make the dipping sauce: Combine the soy sauce, vinegar, sesame oil and green onions in a small bowl. Serve with hot potstickers.