In a non-reactive bowl, mix together olives, tomatoes, capers, onion, garlic, dill, thyme and several grinds of black pepper. Cover and store in the refrigerator until ready to use. (Tapenade can be made up to 3 days ahead. Bring to room temperature when ready to use.)
To prepare the chicken, place breasts in a shallow nonreactive dish, and toss with lemon juice. Marinate, turning once or twice, at room temperature 30 minutes.
Arrange a rack at center position and preheat oven to 350 degrees.
Mix together thyme, salt and pepper in a small bowl. Pat chicken breasts dry and coat both sides with some of the thyme mixture.
Heat olive oil in a large, ovenproof skillet set over medium-high heat. Sauté chicken until golden on both sides, 2 minutes or more per side. Place pan with chicken in oven and bake until juices run clear when chicken is pierced with a sharp knife, about 10 to 12 minutes.