Preheat the oven to 350°F.

Season the chicken with salt and pepper.

Heat olive oil in a large enameled cast-iron casserole.

Brown half of the chicken, backbone, and neck over moderately high heat (4 minutes per side).

Transfer the browned chicken to a plate and repeat with the remaining chicken.

Pour off excess fat, leaving 2 tablespoons in the casserole.

Add onion, garlic, raisins, and walnuts to the casserole.

Cook over moderate heat until the onion is softened and golden brown (about 7 minutes).

Add saffron water, chicken broth, pomegranate juice, cardamom, allspice, dried lime, and cinnamon stick.

Bring the mixture to a boil over moderately high heat.

Return the chicken pieces to the casserole, skin side up, along with any accumulated juices.

Cover and braise in the oven for about 35 minutes, until the chicken breasts are cooked through.

Transfer the chicken breasts to a medium bowl and keep them warm.

Continue braising the dark meat pieces for about 15 minutes, until the legs are cooked through.

Transfer the legs to the bowl.

Discard the chicken back and neck.

Boil the braising liquid over high heat until it is reduced to 3/4 cup (about 15 minutes).

Discard the dried lime, cardamom, allspice, and cinnamon stick.

Add red wine vinegar and season the sauce with salt and pepper.

Return the chicken pieces to the sauce and simmer gently until heated through (about 3 minutes).

Transfer the chicken stew to shallow bowls and serve with couscous.