Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add pork; cook 6 minutes or until done, stirring to crumble. Add onions, soy sauce, and sesame oil; cook 30 seconds. Stir in coleslaw, and cook 30 seconds or until cabbage wilts, stirring frequently.
Combine 3 tablespoons water and cornstarch in a small bowl. Add cornstarch mixture to pork mixture; cook 1 minute, stirring constantly. Remove from heat; cool to room temperature.
Working with 1 gyoza skin at a time (cover remaining skins to prevent drying), spoon 1 scant tablespoon pork mixture into center of each skin. Moisten edges of skin with water. Fold in half, pinching edges together to seal. Place on a baking sheet in a single layer (cover loosely with a towel to prevent drying). When all skins are filled, remove towel and cover with plastic wrap; freeze until firm. Place in zip-top plastic bags, and freeze for up to 3 months.
Arrange the frozen pot stickers in a single layer on a baking sheet; cover with plastic wrap, and thaw in refrigerator overnight.
Heat peanut oil in a large nonstick skillet over medium heat. Arrange pot stickers in pan in a single layer; cook 2 minutes or until browned on bottom. Add 1 cup water to pan; cover and cook 5 minutes. Uncover and cook until liquid evaporates, about 2 minutes. Serve immediately.