Combine first 4 ingredients in a shallow dish. Dredge chicken in flour mixture. Heat oil in a nonstick skillet coated with cooking spray over medium-high heat. Add chicken, and cook 4 minutes on each side or until browned. Remove chicken from pan; keep warm. Add bell pepper, onion, broth, and vinegar to pan; cook 5 minutes or until vegetables are soft, stirring frequently. Spoon bell pepper mixture into a bowl; stir in 2 tablespoons cheese. Return chicken to pan, and sprinkle with 2 tablespoons cheese. Cover; cook over low heat 2 minutes or until cheese melts. Divide the vegetable mixture evenly between 2 plates, and top each serving with a chicken breast half. Garnish with oregano sprigs, if desired.