1
For the Chicken: In a small bowl, whisk together the yogurt and balsamic vinegar until blended. In a plastic food-storage bag, combine chicken and yogurt mixture. Seal and turn the bag to coat. Marinate in the refrigerator for 20 minutes.
2
Meanwhile, heat a gas grill or grill pan to medium-high.
3
For the Tomato-Mozzarella Topping: In a large skillet, heat oil over medium heat. Add the onion and saute about 5 minutes or until onion is slightly softened and the wedges fall into pieces. Add the balsamic vinegar and water. Bring to a simmer. Reduce heat to medium-low; cook about 7 minutes until liquid is reduced and onion is tender.
4
Increase heat to medium-high and add tomatoes, salt and pepper. Cook for 2 minutes and remove from the heat. Let mixture cool for 2-3 minutes then stir in mozzarella cubes and basil gently.
5
Remove chicken from bag. Discard marinade. Gently rinse chicken and pat it dry with paper towels. I know, sounds weird, but do it.
6
Spray grill with cooking spray or coat with oil. Grill for 6-8 minutes per side. Serve immediately. Serve chicken on platter with topping in the center and let guests spoon their topping on.
