If your grapes have seeds, slice them in half and flick out the seeds with the point of a knife.
As for the meat, chicken legs take a little longer to cook than breasts. I purée the sauce, but for a more rustic presentation leave the vegetables, grapes and juices as they are.
You can do this in a skillet and transfer to an ovenproof casserole if you do not have a Dutch oven. You can reheat this by cooking the chicken 10 minutes less, puréeing the sauce and then baking for 25 minutes at 300 F uncovered or until chicken juices run clear.
4 chicken legs and 4 breasts on the bone
Salt and freshly ground pepper
2 tablespoons olive oil
2 cups sliced onion
½ cup sliced carrot
2 tablespoons fresh chopped tarragon
1 pounds red grapes, halved (about 3 cups)
¼ cup balsamic vinegar
Preheat oven to 300 F.
Season chicken pieces with salt and pepper. Heat oil in a Dutch oven or ovenproof casserole over medium heat. Brown chicken pieces in batches, skin-side down first, about 3 minutes a side. Remove chicken from casserole and reserve. Drain off all but 2 tablespoons fat.
Return casserole to heat. Add onion and carrot and sauté for 1 minute. Add tarragon, grapes and balsamic vinegar, bring to boil, then return chicken legs to pan, skin-side up.
Cover and bake for 10 minutes. Add breasts and continue to bake, basting occasionally, for 35 minutes or until juices run clear.
Remove chicken to a serving plate and keep warm. Skim fat from casserole and scrape contents into a food processor. Process until smooth. Season with salt and pepper to taste. Serve chicken with sauce. Garnish with extra grapes and fresh tarragon.