Prep - Prepare grill to medium heat. Using 2 tablespoons balsamic vinegar, brush both sides of peaches. Place peaches on grill, turning and brushing with vinegar occasionally, until caramelized and softened (about 5 minutes).
Combine - Remove from grill and place each half, face up, on a dessert plate.
Create - Top with ice cream and drizzle with remaining balsamic vinegar. Garnish with mint, if desired.