Preheat oven to 180C (350F).

Place onion and oil in roasting pan or ovenproof casserole dish and bake for 30 minutes. Meanwhile wash the chicken and pat dry with paper towel. Season chicken well with salt and pepper and add to the onion tray.

Scatter over red capscium, sherry or wine, saffron and the soaking liquid, almonds, rosemary and tomatoes. Cover with foil and bake for an hour.

Remove cover and baste chicken with the pan juices. Increase temperature to 200C (400F) and cook for another half an hour to an hour, or until chicken is browned and cooked through. To check that the chicken is done, cut down the inside thigh until you can see the bone. If the flesh looks pink return the chicken to the oven for a while longer.

When the chicken is cooked, allow to rest for 10 minutes before carving.