How to Make It
Make the dumplings In a food processor, pulse the chives, ginger, garlic, soy sauce, rice wine, brown sugar, both sesame oils and 1 teaspoon of salt until finely chopped. Transfer to a large bowl; mix in the pork.
Line a large baking sheet with parchment paper. Spoon about 1 tablespoon of the filling into the center of 1 gyoza wrapper and, using your finger, moisten half of the edge with water. Fold the dough up and over the filling to form a half-moon and pinch to seal the dumpling completely. Moisten the top of one end with water, bring the other end over and pinch to bring together and create a rosebud shape. Place the dumpling on the parchment-lined baking sheet and keep covered with a clean kitchen towel while you assemble the rest. Repeat the process with the remaining filling and wrappers.
Line 2 large steamer baskets with cabbage leaves and set the dumplings on the cabbage. Set the basket in a pot of boiling water and steam until the wrappers turn transparent and the filling is firm, 8 to 10 minutes.
Meanwhile, make the dipping sauce In a small saucepan, simmer the stock over moderately high heat until reduced by half, about 2 minutes. Whisk in both vinegars and the ginger. Serve the warm dipping sauce with the dumplings.