Grilled Chicken with Fresh Grape Glaze

Ingredients

• 3 cups seedless red grapes
• 2 tsp olive oil
• 1 cup chopped onion
• 2 garlic cloves, minced
• 2 tbsp balsamic vinegar
• 2 tsp low-sodium soy sauce
• 1 tsp brown sugar
• 1 tsp chopped fresh rosemary
• 1 tbsp olive oil
• 6 chicken drumsticks (about 1 1/2 pounds), skinned
• 6 chicken thighs (about 1 1/2 pounds), skinned
• 2 tsp chopped fresh rosemary
• 1 tsp freshly ground black pepper
• 3/4 tsp salt
• Cooking spray
• Fresh rosemary leaves (optional)