1 cup dry red wine
1/4 cup sugar
1 medium shallot, finely chopped
1 garlic clove, smashed and peeled
Leaves from 1 sprig fresh rosemary, finely chopped (about 1 1/2 teaspoons)
Kosher salt and freshly ground black pepper
8 pieces mixed chicken thighs and drumsticks, about 2 1/2 pounds
1/2 cup seedless black grapes, halved
1/2 cup seedless red grapes, halved