Season the chicken pieces with salt and pepper. In a large sauté pan with a lid heat
Add the garlic, cover the pan and cook over a low heat for 10 minutes. Holding the cover on the Pan to prevent the chicken falling out, pour off the excess fat. Add the vinegar to the pan and simmer, uncovered, for about 10–15 minutes until the sauce is well reduced. Add the tomatoes, tomato purée and bouquet garni, cover and simmer for 10 minutes more, or until the chicken is tender. Transfer the chicken to a serving dish, trimming the leg bones with poultry shears or a knife to neaten them, and keep it warm.
Add the stock to the pan and simmer the sauce uncovered until it is thick and concentrated, about 5 minutes, and then if the garlic is not soft, cook it for 5–10 minutes longer. Work the sauce through a sieve, pressing hard to extract the purée from the garlic. The chicken, and sauce, can be kept for up to three days in the refrigerator, or can be frozen. If you are doing this, reheat the chicken in the sauce if necessary and taste it for seasoning. Take it from the heat and arrange the chicken pieces on a serving dish.
To finish, whisk the remaining butter into the sauce in small pieces, taste it for seasoning and spoon it over the chicken. Sprinkle the dish with chopped parsley and serve at once.