How to Make It
In a small bowl, toss the cabbage with the salt and let stand until wilted, about 10 minutes; drain and squeeze dry. In a medium bowl, mix the pork with the cabbage, cornstarch, pepper, scallions, garlic, ginger, tamari and sesame oil. Cover the filling and refrigerate until ready to use.
In a small bowl, whisk the tamari with the vinegar, sesame oil, sugar, garlic, ginger and black pepper. Let stand for at least 15 minutes, then strain.
Meanwhile, in the bowl of a food processor, process the flour, sweet rice flour and salt. With the machine on, slowly stream in the boiling water until a dough forms.
Divide the dough into 2 pieces and place 1 piece of dough in a resealable plastic bag. Roll out the other piece of dough on a flour-dusted piece of parchment paper into a 16-inch rope about 3/4-inches thick. Cut the rope into rounds about 3/4 inch wide and put the rounds in the resealable bag. Roll out and cut the remaining dough.
Working with one dough round at a time, use the palm of your hand to gently flatten, then roll out to form a circle about 1/16 inch thick. Spoon about 1 tablespoon of filling in the center of each 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 or pleat to seal the dumpling completely. Place the dumplings on a parchment-lined baking sheet.
Meanwhile, in a large nonstick frying pan with a tight-fitting lid, heat the oil until hot but not smoking. Add about half of the dumplings in a single layer and fry over moderately high heat until crunchy and golden, about 3 minutes. Carefully pour 1/3 cup of water into the pan and cover immediately. Steam the dumplings over moderately low heat until cooked through, about 12 minutes. Remove the lid cook over moderately high heat until the water evaporates. Cook the remaining dumplings and serve with the dipping sauce.