Mix cabbage and salt in a large bowl and let stand 30 min. Wring out cabbage and mix with mushrooms, pork, scallions, soy sauce, sesame oil, mirin, ginger, cornstarch and pepper.
Place wonton wrapper on a flat surface. Brush with water, add a spoonful of filling and press closed in a triangle. Repeat with remaining wrappers and filling.
Heat canola oil in a large non-stick skillet. Add 10-12 potstickers in a single layer and sauté until brown. Add ¼ c stock, cover and let steam 3-4 minutes. Remove from pan and repeat with remaining potstickers until all are cooked. Serve with dipping sauce. Makes 40-45 potstickers
Ginger-Soy Dipping Sauce
Whisk together all ingredients and chill.