To prepare chutney,
place mango on grill rack coated with cooking spray; grill 4 minutes on each side. Cool and chop. Set aside.
Heat oil in a small saucepan over medium-high heat. Add onion; sauté 4 minutes. Add ginger; sauté 1 minute. Add vinegar, 2 tablespoons sugar, juice, 1/4 teaspoon salt, and pepper; cook 5 minutes or until liquid almost evaporates. Stir in mango; cook 1 minute. Remove from heat. Stir in watermelon, cilantro, and mint. Add mint sprigs and lime wedges, if desired.
serve along side your favorite grilled meat....