In a small saucepan, mix together orange zest, orange juice, granulated sugar, soy sauce, apple cider vinegar, grated garlic, ground ginger, and red pepper flakes.
Zest from one orange, 1 cup (about 2-3 oranges) freshly-squeezed orange juice, ¼ cup granulated sugar, 2 tablespoons low-sodium soy sauce, 2 tablespoons apple cider vinegar, 2 cloves garlic, ¼ teaspoon ground ginger, ¼ teaspoon red pepper flakes