In a medium sauce pan, add in 1 cup soy sauce, 1/2 cup rice vinegar, 1/2 cup brown sugar, 2 tablespoon cornstarch, 1 teaspoon ground ginger, 1/2 teaspoon crushed red pepper flakes and 4 teaspoons minced garlic. Stir until combined and then turn heat to medium-high.
Place the saucepan over medium-high heat and bring the mixture to a boil, stirring frequently. Reduce the heat to a simmer and cook until the sauce has thickened enough to coat the back of a spoon, about 3-5 minutes. Remove from heat and let cool before using.