Prepare the filling; combine all of the ingredients, except the dumpling wrappers, in a medium bowl. Bring a small saucepan of water to a boil. Add 1 teaspoon filling, and cook until no longer pink. Taste, and adjust the seasoning, if necessary.
Place a dumpling skin on work surface. Using your finger, wet around the edges with water. Place 1 1/2 tablespoons filling in the center. Fold dumpling skin over to enclose. Pinch the edges together to form a half moon. Pleat the rounded edge. Set aside. Repeat with remaining filling and wrappers.
Prepare dipping sauce; combine all the ingredients in a small saucepan. Heat gently, whisking, until emulsified. Be sure not to boil. Set aside to cool.
Just before serving, bring a large pot, fitted with a steamer insert lined with lightly oiled parchment paper with a few holes poked in it, to a simmer. Add dumplings and simmer until cooked through, 5 to 7 minutes.