Melt butter in a large skillet over medium-high heat; add chicken, and cook 3 to 4 minutes on each side or until golden brown. Remove chicken from skillet; add bell pepper and onion, stirring often, 4 to 5 minutes or until vegetables are tender. Return chicken to skillet.
Wisk together broth and next 2 ingredients, and pour over chicken. Cover, reduce heat to low, and simmer 20 minutes or until chicken is done.