Place each chicken breast half between 2 sheets of heavy-duty plastic wrap. Flatten each breast half to 1/2-inch thickness using a meat mallet or rolling pin. Combine herbes de Provence, salt, pepper, and 2 garlic cloves, and rub mixture over both sides of chicken.
Place a large nonstick skillet coated with cooking spray over medium-high heat until hot. Add chicken; cook 3 minutes on each side or until done. Remove from skillet. Recoat skillet with cooking spray. Add onions and bell peppers, and sauté 5 minutes or until tender.
Combine tomato sprinkles, vinegar, oil, and 2 garlic cloves; stir well with a whisk. Place 1 1/2 cups salad greens on each of 4 plates; top each serving with a sliced chicken breast half and 1/2 cup bell pepper mixture. Drizzle 2 tablespoons vinegar mixture over each salad; top each with about 1 tablespoon olives.