For the dumplings: Place the minced cabbage and 1 teaspoon of the salt in a large bowl. Mix well and let the salt leach the cabbage of water for 20 minutes.
Meanwhile, make the dipping sauce by whisking together all the ingredients in a small bowl. Set aside until ready to serve.
For the filling, combine the pork, water chestnuts, green onions, ginger, garlic, soy sauce, rice wine, sesame oil, sugar, pepper, cornstarch, and the remaining 1/2 teaspoon salt in a large bowl and mix well.
Use your hands to squeeze the water out of the minced cabbage. Discard the water and mix the dry cabbage with the pork until well combined. Chill until ready to make the dumplings.
Sprinkle a baking sheet lightly with cornstarch. To form the dumplings, place a wrapper in your palm and brush water along the edge. Spoon a heaping tablespoon of filling in the center of the wrapper. Gather up the edges to form a basket. This is a dumpling that is open at the top.
Place the dumpling on the baking sheet, making sure to flatten the bottom of the dumpling so it sits upright. Press any excess filling down into the dumpling and press a piece of carrot and a pea in the filling to secure. Repeat with the remaining filling and wrappers. (You may have wrappers left over.)
Bring a large pan or wok filled with 2 inches of water to a boil over high heat. Place a steaming rack in the wok. Line 2 plates with a single layer of cabbage leaves. Place 8 to 10 dumplings on each plate, leaving plenty of space between them. Set one plate of dumplings on the steaming rack, cover the pan with a lid and steam the dumplings for 10 minutes. Transfer the steamed dumplings to a warmed platter and serve them right away with the dipping sauce. Repeat with the remaining dumplings.