Prepare the Cabbage: Chop the nappa cabbage, sprinkle with salt, and massage it to sweat out the water. Drain and set aside.
Make the Filling: In a bowl, combine ground pork, chopped chives, brown sugar, minced garlic, sesame oil, chicken stock, and the drained cabbage. Mix well.
Fill the Dumplings: Take a dumpling wrapper, place a spoonful of filling in the center, and fold the wrapper, creating pleats to seal.
Steam the Dumplings: Place the dumplings in a bamboo steamer lined with parchment paper. Steam over boiling water for about 10 minutes.
Prepare the Sauce: Mix Chinese vinegar, soy sauce, chili oil, sesame seeds, and chopped scallions in a bowl.
Serve: Serve the dumplings hot with the dipping sauce.