Slice the breasts in half if they are really big. Pound the chicken breasts. This makes it more juicy and delicious after grilling. There are a few ways to pound the chicken, I like to put it in a large ziplock bag and use a mallet or a rolling pin.
In a large bowl, add the chicken 1 tsp oil and all the seasonings. Rub the chicken on all sides.
Heat a grill pan, skillet or grill on medium high heat. If cooking on the stovetop, add 1 tsp of oil to the skillet.
Add the chicken to the hot skillet or grill. Cook it for about 7-8 minutes on each side or until chicken is 165º internally.
While the chicken is cooking, combine the tomatoes, onions, basil, salt pepper and 1-2 Tbsp of balsamic glaze. Mix well.
When the chicken is just a few minutes out from being cooked through (about 12-15 minutes) Add the mozzarella slices. If grilling, close the lid. If in a skillet, cover it for just 1-2 minutes to melt the cheese.
Let the chicken rest, spoon the tomato salad over the top. Serve with an extra drizzle of balsamic and enjoy.