In a large skillet brown chicken in hot oil over medium-high heat for 5 minutes, turning once. Remove chicken from skillet; set aside. Add onion to skillet. Cook over medium heat for 8-10 minutes or until tender and lightly browned, stirring occasionally and adding garlic the last 1 minute of cooking.
Stir tomatoes, olives, capers, lemon peel, and oregano into onion mixture. Place chicken on tomato mixture. Bring to boiling; reduce heat. Simmer, covered, 13-15 minutes or until chicken is no longer pink (170 degrees F).
To serve place chicken on platter. Season tomato mixture to taste with salt and black pepper. Spoon tomato mixture over chicken Sprinkle with parsley and serve.