Place all ingredients into a small saucepan, except cornstarch, and stir together.
Simmer mixture for 3 to 4 minutes. Remove from heat and allow mixture to cool completely before using as marinade.
Combine cornstarch with ¼ cup water and whisk together to create a slurry.
Stir cornstarch slurry into sauce mixture and stir together. Simmer for 1 minute while stirring, until sauce thickens enough to coat the back of a spoon.
Remove sauce from heat and cool.
