1. Season chicken with pepper, thyme, and marjoram. In a large frying pan, heat olive oil. Add chicken and cook in 2 batches over medium-high heat, turning once or twice until browned, about 7 minutes per batch. Remove chicken from pan.
2. In drippings, cook onion and celery, stirring occasionally, until softened, 3 to 5 minutes. Stir in broth, tomatoes, and vinegar. Bring to a boil; reduce heat to medium-low. Return chicken to pan.
3. Cover and simmer 15 to 20 minutes, until chicken is tender and white throughout. Stir in olives and cook, covered, 5 minutes longer.