Heat a grill pan to a high heat for about 2-3 minutes. Season both sides of the chicken with black pepper and sea salt.
Place the chicken breasts on the grill pan. Lower the heat to medium-high and cook for 3-4 minutes on the first side, undisturbed. Flip, and cook on the other side for 2-3 minutes. Remove from the pan, place in a bowl, and set aside.
Use the same pan to grill the tomatoes. Grill them on one side for 1 minute, then remove from the heat and set aside.
Heat the olive oil in a large pan over medium heat. Add onion, and cook, stirring, for 3-4 minutes until translucent. Add garlic and cook for 1 minute, stirring constantly. Add red wine, tomato passata, chopped black olives, and rosemary sprigs. Bring to a boil.
Add grilled chicken, lower the heat, and cover. Simmer, stirring occasionally, for 15 minutes or until the chicken is tender. Remove the lid, add green olives and grilled cherry tomatoes. Cook for 5 more minutes. When the meal is ready, remove rosemary sprigs using tongs. Divide between 4 plates and serve hot. We recommend serving with gluten-free pasta or mashed potatoes.
