Grilled Chicken with Grape and Onion Salsa

4 boneless, skinless chicken breasts

Marinade:
1/3 cup olive oil
2 cloves garlic, minced
2 tsp dried basil
1 tsp soy sauce
1/2 tsp ground black pepper

Grape Salsa:
2 cups Concord or red grapes (you can also mix the red grapes with some green), halved (or quartered if grapes are big)
2 small shallots, thinly sliced
2 tsp balsamic vinegar
1 tsp finely chopped fresh rosemary leaves (optional)
1/4 tsp freshly ground black pepper

Preheat oven to broil or grill. Pound chicken breasts to ¼-inch (½-cm) thickness in a large resealable plastic bag. Combine marinade ingredients in a bowl. Add to the plastic bag and let sit for 15 minutes or up to 4 hours. Broil or grill chicken for 4–5 minutes per side, until cooked through. Serve warm or room temperature with salsa. To prepare salsa, mix all the ingredients in a bowl. Let flavors meld for about 15 minutes. Serve over chicken.