
Place the flour in a large bowl and gradually stir in the water until a shaggy dough forms. Knead for 8 to 10 minutes, or until smooth and elastic. Cover with a damp towel and let the dough rest for 1 hour.
Meanwhile, soak the dried shiitake mushrooms in hot water for 20 to 30 minutes, until softened. Drain well, squeeze out any excess water, and finely chop them. Finely chop the fresh shiitake mushrooms and the onion as well.
Heat 2 tbsp vegetable oil in a skillet over medium heat. Add the onion and cook until softened and translucent. Stir in the fresh and rehydrated shiitake mushrooms and cook for 8 to 10 minutes, until the mixture is fragrant and most of the moisture has cooked off. Let cool slightly.
Transfer the mushroom mixture to a large bowl with the ground chicken, sesame oil, soy sauce, sugar, Shaoxing wine, and the remaining 3 tbsp vegetable oil. Stir in one direction for 4 to 5 minutes, until the filling becomes sticky and well combined.
Divide the rested dough into 48 equal pieces. Roll each piece into a circle about 3 1/2 inches wide, keeping the center slightly thicker than the edges. Place about 1 tbsp filling in the center, pleat the wrapper, and pinch tightly to seal. Arrange the finished dumplings on a parchment-lined tray so they do not touch.
To freeze, place the tray in the freezer until the dumplings are firm, then transfer them to freezer bags. To pan-fry, heat a little oil in a nonstick or cast-iron skillet over medium-high heat, add the dumplings, and cook until the bottoms are lightly golden. Pour in enough water to come about 1/4 inch up the sides of the pan, cover, and steam until the water evaporates. Uncover and cook for 1 to 2 minutes more, until the bottoms are crisp and golden. To boil instead, cook the dumplings in gently boiling water until they float, then cook for 2 to 3 minutes longer.




