Step 1

Heat balsamic vinegar in a small saucepan over medium heat. Bring vinegar just to a boil then reduce heat slightly and allow to simmer, stirring occasionally, until vinegar has reduced by half, about 10 minutes. Remove from heat and set aside.

Step 2

Brush grill grates lightly with oil and pre-heat grill to medium-high heat. In a small bowl, stir together olive oil and garlic.

Step 3

Brush each side of each chicken breast lightly with olive oil mixture and season each side with salt and pepper.

Step 4

Transfer chicken to preheated grill, cover with lid and cook chicken 5 minutes, then rotate and cook opposite side until chicken is cooked through and registers 165 degrees on an instant read thermometer (about 5 minutes longer, time will vary though based on the thickness of the chicken breasts).

Step 5

Top each chicken breast with one slice of fresh mozzarella and 1 or 2 Roma tomato slices. Transfer to a platter and cover with foil, allow to rest 5 - 10 minutes.

Step 6

Remove foil and sprinkle tops with fresh basil and drizzle with balsamic reduction, serve immediately.