Slice cabbage coarsely; add to blender. Add water to cover cabbage. Cover and blend on high for 2 seconds. Drain and repeat until all cabbage is shredded. Squeeze cabbage to remove moisture. blanch, rinse, and finely chop chives. Combine cabbage, chives, chicken, salt, soy sauce, and sesame oil; mix well. Put 1 tablespoon of filling in center of each pi. Fold wrapper in half and seal edges.
Bring water to a boil, add dumplings and cook 5 minutes. Rinse dumplings under cold water to prevent from sticking together. Serve with soy sauce, vinegar, and ginger.
Makes 4 servings.