Combine first 10 ingredients; stir in 1/8 teaspoon salt and 1/4 teaspoon black pepper, tossing well to combine.
Sprinkle chicken evenly with remaining 3/8 teaspoon salt and 1/4 teaspoon black pepper. Coat chicken with cooking spray. Place chicken on a grill rack coated with cooking spray; grill 5 minutes on each side or until done. Serve with salsa; garnish with mint sprigs, if desired.