In 10-inch skillet, heat 1 tablespoon oil over medium heat. Add garlic, gingerroot, orange peel and pepper flakes; stir-fry about 30 seconds or until fragrant. Add broth, 2 teaspoons soy sauce, the vinegar and sugar; stir about 30 seconds or until sugar dissolves. Stir orange juice mixture, then add it to skillet. Heat sauce to boiling, stirring. Reduce heat to low; simmer 1 minute. Transfer sauce to bowl; wipe out skillet.