Meanwhile, in 10-inch nonstick skillet, heat oil over medium-high heat. Cook onion in oil 6 to 7 minutes, stirring frequently, until softened and beginning to caramelize slightly. Add bell pepper; cook 4 to 5 minutes longer or until tender. Add chicken and teriyaki sauce to skillet. Cook about 2 minutes longer or until sauce evaporates slightly and chicken is warmed through.