Combine the first 11 ingredients in large bowl. Working with 1 won ton wrapper at a time (cover the remaining wrappers with a damp towel to keep them from drying out), spoon about 1 tablespoon turkey mixture into center of each. Moisten edges of wrapper with water; bring the 2 opposite corners together. Press edges together with a fork to seal, forming a triangle. Place dumplings on a large baking sheet sprinkled with 2 teaspoons cornstarch.
Line bottom of each rack of a bamboo steamer with cabbage leaves. Place the dumplings 1/2 inch apart on steamer racks (about 6 or 7 per rack), and cover with steamer lid. Add water to a wok to a depth of 1 inch, and bring to a boil. Place steamer in wok, and steam for 20 minutes. Carefully remove the dumplings and cabbage from steamer. Repeat with remaining dumplings. Serve with Cantonese Dipping Sauce.