Toss finely chopped napa cabbage with 1/2 teaspoon salt and let stand 10 minutes. Wrap in a clean kitchen towel or several layers of cheesecloth and squeeze firmly to remove excess liquid.

In a bowl combine squeezed cabbage, pork, scallions, ginger, garlic, 1 tablespoon reduced-sodium soy sauce, sesame oil, cornstarch and white pepper. Stir until evenly combined and lightly sticky. Keep refrigerated until ready to fill; do not taste raw filling.

Keep wrappers under a barely damp clean towel. Divide the filling evenly among the 24 wrappers, about 1 heaping tablespoon each, keeping the edge clean. Lightly dampen the edge with water, fold into a half-moon and pinch firmly closed. Add simple pleats if desired; do not overfill or force a seal. Set on a lined tray and cover. If your wrappers are smaller, use less filling and extra wrappers; the yield and nutrition per dumpling will change.

Line a bamboo or metal steamer with suitable perforated parchment. Add enough water to the pot or wok for steady steaming without water touching the dumplings, following your steamer's instructions. Bring to a boil. Arrange dumplings with about 1 inch between them; cook in two batches if necessary.

Cover and steam over steadily simmering water for approximately 10–12 minutes per fresh batch. Check a dumpling's center with a thin-tip thermometer: ground pork must reach 160°F (71°C). Continue steaming if needed. Timing varies with wrapper thickness and filling size. Maintain the water level with boiling water as needed and lift the lid away from your face.

Mix 2 tablespoons reduced-sodium soy sauce, 2 tablespoons rice vinegar and 1 tablespoon water. Serve hot dumplings with sauce divided among four dishes. Let a fresh dumpling cool briefly before biting.