Asian-style hot mustard and reduced-sodium soy sauce for dipping
Stir together all ingredients, except wrappers, and 1/4 tsp salt.
Put a rounded tsp filling in center of a wrapper. Lightly brush edge of wrapper with water, then fold in half (diagonally if square) and press to seal. Form a tortellini shape by moistening 1 corner and bringing 2 corners together, pressing them. Form remaining dumplings.
Cook dumplings in 2 batches in a medium pot of gently simmering water until filling is just cooked, about 3 minutes per batch. Transfer with a slotted spoon to a platter. Keep warm, covered.