These dumplings are always a hit and are great boiled or pan-seared. Try substituting ground chicken or minced shrimp as a variation. They freeze well, so be sure to double the recipe to make more.
To make the dipping sauce, whisk together all of the ingredients in a small bowl. Set aside until ready to serve.
Place the cabbage and salt in a large bowl and mix well. Set aside for 20 minutes to let the salt leach excess water from the cabbage.
In a large bowl, combine the pork, mushrooms, scallions, ginger, garlic, soy sauce, sesame oil, cornstarch, and white pepper and mix well.
Use your hands to squeeze all the water out of the cabbage. Discard the excess water, add the cabbage to pork filling, and mix until well combined.
To make the dumplings, place a dumpling wrapper on your palm, brush water around the edge, and fill the center with a heaping tablespoon of filling. Fold the wrapper in half to form a half-moon. Use your thumb and index finger of one hand to fold 4-5 pleats across the back side of the dumpling, pressing the edges together to seal the dumpling. Gently curve the dumpling so that it sits up when placed on a flat surface. Repeat to make the remaining dumplings.
Lightly dust a baking sheet with cornstarch. Place the finished dumplings on the baking sheet and cover with a damp towel. (To serve at a later date, freeze the dumplings in a single layer until they are hard and then transfer to a sealable plastic bag. Steam the dumplings directly from the freezer for 10 minutes.)
To cook the dumplings, heat a large nonstick skillet over medium heat. Add 1 tablespoon of the canola oil to the hot pan. Place 8-10 dumplings in the pan and brown the bottoms until golden brown, 1-2 minutes.
Add ¼ cup of the water to the pan, cover with a lid, and steam until all of the water evaporates, 6-7 minutes. Transfer the cooked dumplings to a warmed platter and cover with foil. Cook the remaining dumplings and serve warm with the ginger-soy dipping sauce.