Preparation

Make the dough

• Sift the flour into a bowl. Gradually add 1/2 cup cold water, mixing with a wooden spoon until a shaggy dough forms. Turn the dough onto a lightly floured surface; knead until smooth and springy, about 5 minutes. If the dough feels stiff as you work, add a little more water 1 Tbs. at a time, but don’t exceed 3/4 cup total. Put the dough in a clean bowl, cover it with a towel, and let it rest at room temperature for 20 minutes.
• Put the rested dough on a lightly floured surface and knead it for 2 minutes. Divide the dough and shape each half into a 12-inch-long cylinder that’s about 1 inch in diameter. With a serrated knife, cut each cylinder crosswise into 24 rounds. Lay the rounds on a lightly floured surface and flatten with the palm of your hand to about 1/4 inch thick. Sprinkle flour lightly on the pieces to prevent sticking. With a rolling pin, roll each slice into a 3-inch round about 1/8-inch thick. Pinch the edges of the rounds to make them thinner than the middle. Arrange the rounds in a single layer on a lightly floured tray or baking sheet and cover with a towel.

Make the filling

• Soak the dried mushrooms in warm water for 15 minutes; drain. Cut off and discard the stems; finely chop the mushroom caps.
• In a wok or large skillet, heat 2 Tbs. of the canola oil over medium-high heat. Add the dried and fresh mushrooms; stir-fry for about 2 minutes. Add the soy sauce and sesame oil; stir briefly. Remove the mushrooms and set aside. Pour the remaining oil into the wok. Add the celery, cabbage, and ginger; stir-fry for about 3 minutes. Season with salt and pepper. Stir in the cooked mushrooms. Transfer the mixture to a colander to drain before wrapping.

把饺子

• Put about 2 tsp. of the filling in the middle of a wrapper. Brush the edges of the dough with a little water. Fold the wrapper in half and pinch the edge in the middle of the rounded part of the half-moon. Make two small pleats in the wrapper surface closest to you on either side of the pinched middle by gathering the dough and folding it over onto itself. Point the pleats toward the middle of the dumpling. Seal the pleated and unpleated sides by pinching along the top.

Cook the dumplings

• Arrange the dumplings, pleated side up and not touching, on a bamboo steamer lined with cheesecloth or wilted cabbage leaves. Fill a wok or a large pot with 2 inches of water and bring the water to a boil. Cover the steamer and set it on the wok. Steam over high heat for 15 minutes. Serve the dumplings in the bamboo steamer set on a large plate to catch any water that might drip.

Make Ahead Tips

To freeze uncooked dumplings, arrange them in a single layer on a parchment-lined baking sheet, and freeze until solid. Transfer to a sealed plastic container, with parchment or waxed paper separating the layers. You don’t need to defrost the dumplings before cooking: just cook them a few minutes longer than usual.