In a large bowl, combine the pineapple, mangoes and peaches. Spray generously with cooking spray. Toss and spray again to ensure the fruit is well coated. Sprinkle with brown sugar. Toss to coat evenly. Set aside.
In a small saucepan, heat the balsamic vinegar over low heat. Simmer until the liquid is reduced in half, stirring occasionally. Remove from the heat.
Prepare a hot fire in a charcoal grill or heat a gas grill or broiler. Away from the heat source, lightly coat the grill rack or broiler pan with cooking spray. Position the cooking rack 4 to 6 inches from the heat source.
Place the fruit on the grill rack or broiler pan. Grill or broil over medium heat until the sugar caramelizes, about 3 to 5 minutes.
Remove the fruit from the grill and arrange onto individual plates. Drizzle with balsamic vinegar and garnish with mint or basil. Serve immediately.