HEAT 1 Tbsp. oil in large nonstick skillet on medium heat. Add chicken; cook 6 to 7 min. on each side or until done (165ºF).
MEANWHILE, mix cornstarch, wine and mustard until blended. Heat remaining oil in small skillet on medium heat. Add peppers; cook and stir 5 min. or until crisp-tender. Stir in cornstarch mixture; cook 2 min. or until thickened, stirring constantly.
SERVE chicken topped with pepper mixture.