Heat grill on high heat. Toss the peppers, zucchini, yellow squash and red onion with the first measure of olive oil. Grill the vegetables for about 3 minutes on each side or until just tender. Remove to a cutting board and chop into ½” dice. Place in a bowl and add the fresh basil, and white balsamic vinegar. Season to taste with salt and pepper. Reserve warm to serve with grilled chicken.
Lightly coat thinly pounded chicken breasts with the second measure of olive oil and season to taste with salt and black pepper. Grill chicken for about 2 minutes on each side or until interior is white and juices run clear. Serve on top of the grilled vegetable salsa. Serves four.