Combine the soy and vinegar in a small bowl and stir well to combine. Add the sesame oil and mix (or whisk) to incorporate the oil.
Serve the dipping sauce in small condiment bowls like the one shown on this page.
If you are looking for some other gyoza sauce options try our recipe for a Simple Gyoza Dipping Sauce - with scallions, fresh ginger, teriyaki sauce and brown sugar