Flatten chicken breasts slightly. In a large skillet, cook chicken in oil for 4-6 minutes on each side or until a meat thermometer reads 170°. Remove and keep warm.
Stir the root beer, brown sugar, ketchup, mustard and lemon peel into the skillet. Bring to a boil. Cook and stir for 6-8 minutes or until thickened. Return chicken to skillet; heat through. Yield: 4 servings.