Combine all ingredients in a large saucepan (not aluminium). Bring to boil, then simmer for 5 minutes and cool completely.
Pour marinade over chicken pieces, cover and leave at room temperature for 6 hours or refrigerate for 10 to 12 hours, turning pieces occasionally.
Drain chicken and pat dry with absorbent paper. Strain marinade and reserve both liquid and vegetables.
If bacon is very salty, blanch it. Heat oil and butter in a sauté pan or shallow flameproof casserole dish, and fry bacon until well browned. Remove.
Add chicken pieces, skin side down.
Cook over moderate heat until browned, then turn and brown other side.
Remove chicken, add onions and sauté until lightly browned.
Remove onions, add mushrooms and sautéT until tender. Remove.
Discard all but 30 ml fat, add onion, carrot and celery (from marinade) and cook over low heat until soft but not browned. Sprinkle with flour and cook until foaming.
Stir in reserved marinade and stock, add chicken pieces, garlic, shallots, bouquet garni, salt and pepper.
Simmer over low heat or in oven at 180 ºC for 45 to 60 minutes or until chicken is tender.
Remove chicken, set aside with bacon and keep warm.
Place sautéed onions in a large casserole dish.
Strain sauce over and simmer for 10 minutes, or until onions are tender.
Add mushrooms and simmer 2 to 3 minutes, or until sauce has reduced slightly.
Return chicken and bacon to sauce and season to taste.
Serve coq au vin from dish, sprinkling it with chopped parsley just before serving.