In a stand mixer, mix the flour, salt and boiling water until you have a rough ball shape. Dust your work surface with flour. Remove from the bowl and knead for 10 minutes until smooth. Divide the dough into two and rest for 20 minutes.
Divide each piece of rested dough into 16 even-sized pieces. Roll each piece of dough into a small ball and then flatten it. Dust your working surface again. Take one piece of dough and press it to a round disc. Rotate the wrapper when moving your rolling pin. Repeat the process, rotate the wrapper-roll and rotate the wrapper-roll. The wrappers will have thicker center and thinner edges naturally.
Make the filling; In a large skillet over medium high heat, add 3 tablespoons oil and add the ginger, garlic and onion. Cook until fragrant and onions until translucent. Add the cabbage, tofu and stir-fry for another 3-5 minutes until the veggies are tender and all the liquid released has been cooked off. Transfer the vegetable mixture to a large mixing bowl and allow to cool. Then add the cilantro, chives, white pepper, sesame oil, shaoxing wine, salt, sugar and mix well.
To assemble the dumplings; Place the wrapper in your left hand. Place 1 ~2 tablespoon of the filling in the center of your wrapper. Fix the starting point with the thumb of right hand and begin to fold the edge. Repeat the steps to seal the dumpling completely.
Cook the dumplings in two batches. Heat the oil in a large frying pan over medium heat. Fry the dumplings flat side down for about 2 minutes until a golden crust forms on the bottom. Add the 1/4 cup water and immediately cover with a lid and let the steam cook the dumplings for 8 minutes or until all the water has evaporated. Remove the lid and let the dumplings to cook for a further minute until they lift off from the bottom of the pan easily. You might need a spatula to help them along if they are a little sticky, being careful not to break the wrapper. Repeat with the second batch.
Serve the dumplings in a big plate. Drizzle the spicy sauce on top, or serve on the side for dipping. Enjoy.