Place sweet potato starch in a bowl and set aside.
Boil a generous amount of water in a pot, reserving some for cooking the dumplings later. Pour the boiling water into the bowl with the starch and stir with chopsticks until the mixture forms a dough resembling the texture shown in reference images.
Maintain a rolling boil in the pot. Use chopsticks to pinch off bite-sized portions of the dough and drop them directly into the boiling water. The dumplings will detach upon contact.
Gently agitate the water to ensure all dumplings are submerged. Scoop one dumpling to verify its cooked state—it should appear semi-translucent with a firm texture.
Boil vigorously for 3-5 minutes until the dumplings darken in color. Add napa cabbage, peanut oil, chili oil, white pepper, sugar, and salt. Simmer briefly.
Finish by sprinkling chopped scallions before serving.