Whisk all the ingredients (except sesame seeds) together in a small bowl. Set aside until it's time to use.
If you want to make it ahead and store it for a few days omit the sesame seeds and sprinkle them on right before use. Store refrigerated.
NOTE: We like to use the chili oil "seeds" but you can use only the oil if you wish.
We were testing various ingredients and we found this combination to be very good:
2 tablespoons Sweetened Chinese Black Vinegar
2 tablespoons Oyster Sauce
2 teaspoons Soy Sauce
1 tablespoon Chili Oil (adding seeds or not, to your taste)
1 teaspoon toasted sesame seeds
Whisk all the ingredients (except sesame seeds). Sprinkle the sesame seeds on the sauce right before serving. The Sweetened Chinese Black Vinegar adds sweetness and complexity to the sauce.