Toss the cabbage, garlic, ginger, onion, and scallions in the bowl of a food processor and blitz until everything is finely chopped. Add the tofu, pork, egg, soy sauce, sesame seed oil, 3/4 teaspoon salt, and 1 teaspoon pepper. Pulse until the mixture is just blended together. Don’t over-blitz.
Line 2 large rimmed baking sheets with floured parchment paper and have a pastry brush, a small bowl of water, and a teaspoon close by. Place a dumpling wrapper in the palm of your hand and put about 2 teaspoons filling in the center. Use a pastry brush or your fingertips to lightly moisten the edges of the wrapper with water. Fold the wrapper in half, encasing the filling. Firmly press the edges of the wrapper closed, eliminating any air pockets as you go, to create a half-moon shape.
If you are pan-frying the dumplings, you can leave the dumplings as they are. If you are using the dumplings in soup or steaming them, go a step further and moisten the opposing corner ends of the half-moon and then join the corners together, pressing firmly to secure. We call these dumplings “nuns’ hats.” Place them on the baking sheet and continue with the rest, ensuring there’s a little space in between each dumpling. If you are not cooking the dumplings immediately, dust them with a little more flour and cover them with plastic wrap. Freeze for several hours or overnight on the sheets, and then once the dumplings are completely frozen, place them in resealable plastic bags and store in the freezer until required. They will keep well in the freezer for several months.
To pan-fry the dumplings, cover the base of a large nonstick pan with a thin layer of vegetable oil and place over medium heat. Gently place a batch of the flat dumplings down on their side, making sure the dumplings do not touch. Fry for 2 to 3 minutes, on each side until golden brown and crisp, taking care not to burn them. To steam the dumplings, place as many of the rounded nuns’ hat dumplings as will fit into your steamer basket, keeping a little space in between each one to prevent them from sticking. Place your steamer basket over boiling water and steam on high for 10 to 12 minutes, until the dumpling skin becomes transparent. Serve the dumplings piled onto a plate, with the dipping sauce on the side.