1In 12-inch nonstick skillet, heat oil over medium-high heat. Sprinkle chicken with salt; cook and stir 4 to 5 minutes or until chicken is no longer pink in center. Remove from skillet.
2In same skillet, cook bell peppers and onion over medium-high heat 3 to 5 minutes, stirring frequently, until vegetables are crisp-tender. Return chicken to skillet.
3In small bowl, mix broth, reserved pineapple liquid, vinegar, brown sugar, cornstarch and crushed red pepper flakes; stir into chicken mixture. Add pineapple; heat to boiling. Reduce heat; cook uncovered, stirring frequently, until sauce is thickened and bubbly. Serve over rice.