Springtime Chicken

In a small bowl, whisk together yogurt and balsamic vinegar until well blended. In a plastic bag, combine chicken and yogurt mixture; seal and turn to coat. Marinate in refrigerator for 20 minutes. Meanwhile, heat gas grill to medium-high.

In a large skillet, heat oil over medium heat. Add onion; saute 5 minutes, or until slightly softened (the wedges will fall apart into pieces). Add balsamic vinegar and water. Bring to a simmer. Reduce heat to medium-low; cook about 7 minutes, or until liquid is reduced and onion is tender. Increase heat to medium-high. Add tomato, salt and pepper; cook for 2 minutes. Remove skillet from heat; let cool for 2-3 minutes. Stir in mozzarella and basil.

Remove chicken from bag; discard marinade. Gently rinse chicken; pat dry with paper towels. Grill, turning once, for 6-8 minutes per side, or until internal temperature registers 170* on on instant-read meat termometer. Serve immediately, with topping, or let cool to room temperature.