For the Sauce:
½ cup soy sauce
½ cup black vinegar
1 tablespoon sesame oil
2 teaspoons toasted white sesame seeds
For the Pork Dumplings:
1 pound ground pork
1 cup finely chopped garlic chives
2 teaspoon minced garlic
1¼ teaspoon salt
1 teaspoon cornstarch
1 teaspoon grated ginger
1 teaspoon freshly ground black pepper
Thirty 3½-inch round dumpling wrappers (see note above)
Canola oil, for frying
1. Make the sauce: In a medium bowl, combine all the ingredients and set aside until ready to serve. Makes about 1 cup.
2. Make the pork dumplings: In a medium mixing bowl, combine all the ingredients except for the dumpling wrappers and canola oil, using a rubber spatula to mix everything together.
3. Working with one dumpling wrapper at a time, place a tablespoon of the pork filling in the center of the wrapper and fold in half. Pinch the dumpling at one end before guiding one edge over and folding it to form a pleat, making sure to pinch as you go until you have a total of 6 pleats and the dumpling is closed. Transfer the dumpling to a parchment-lined baking sheet. Repeat with remaining dumpling wrappers until all of the filling has been used. Cover dumplings with a damp paper towel until ready to cook.
4. In a large nonstick skillet, heat 2 tablespoons of oil over medium-high heat. Working in 3 batches, arrange the dumplings in a single layer and cook, until the bottoms begin to brown, about 1 minute. Pour ½ cup water into the pan, cover with a lid and steam until the filling is almost cooked through, about 2 minutes. Uncover and cook, until the all the water has evaporated and the bottoms have become golden brown and crisp, about 2 minutes. Serve warm.