Mix 250g of all-purpose flour with 130g of water and knead into a dough. Cover and rest for 10 minutes, knead again until smooth, then cover and rest for 30-60 minutes.
Mix 300g of finely chopped napa cabbage with ¼ teaspoon of salt and leave for 10 minutes. Squeeze out the water in batches.
Soak 1 tablespoon of dried shrimp in 2 tablespoons of water until soft, then finely chop the shrimp.
Mix 250g of ground pork with the shrimp and its water, 2 chopped scallions, 1 teaspoon of minced ginger, 2 tablespoons of light soy sauce, and 1 pinch of ground Sichuan pepper until absorbed.
Divide the dough into three, roll each part into a rope, and cut it into 10 pieces. Flatten each piece and roll it into a thin round wrapper.
Before wrapping, stir the cabbage and ½ tablespoon of sesame oil into the pork. Divide the filling between the wrappers, fold each in half, and pinch the edges to seal.
Slide the dumplings into a large pot of boiling water. Each time it returns to a boil, add a third of 1½ cups of cold water. Once plump and floating, drain, rinse briefly, and serve.
