In a saucepan, heat 2 tablespoons of vegetable oil over medium heat. Add the minced garlic and ginger and sauté for about 30 seconds until fragrant. Whisk the orange juice, soy sauce, rice vinegar, granulated sugar, cornstarch orange zest, and crushed red pepper flakes in a large measuring cup then pour it over the garlic-ginger mixture. Stir continuously until the sauce begins to simmer. Cook the sauce for about 2-3 minutes or until it thickens, stirring constantly.
2/3 cup orange juice, 3 tablespoons low-sodium soy sauce, 3 tablespoons rice vinegar, 1/3 cup granulated sugar, 1 tablespoons cornstarch, 1 teaspoon grated orange zest, 1/2 teaspoon minced garlic, 1/2 teaspoon minced ginger, 2 tablespoons vegetable oil for cooking the sauce, 1/4 teaspoon crushed red pepper flakes