The day before, chop up the chicken into joints using a very sharp knife (or use chicken pieces on the bone), leaving the skin on each part. Make two or three slashes through the skin on each piece, cutting a little way into the flesh.
Make the marinade by mixing together the vinegar, olives, garlic, capers, prunes, oregano, salt, pepper and oil. Lay the chicken in a shallow glass or stainless steel dish and spoon over the marinade, rubbing it into the cuts. Cover with cling film and chill overnight.
The following day, begin by preheating the oven to 180C/350F/gas mark 4. Lift the chicken from the marinade and drain well, reserving the marinade.
Heat an oven-proof frying pan (or large casserole pot) and add a small amount of sunflower oil. When the pan and oil are hot, fry the chicken pieces skin side down until the skin is a light golden brown. Turn over the chicken, remove the pan from the heat and allow to cool a little. Pour the marinade over the chicken then sprinkle on the brown sugar.
Pour the wine around the chicken in the pan, cover with a lid and cook in the oven for about 20 minutes (a little more if the breasts are thick), basting two or three times during the cooking.
To test if cooked, prick the chicken at its thickest with a skewer and check that the juices run clear with no trace of blood. Lift the chicken onto a warm serving dish and place the pan on the heat. Bring the juices to the simmer and add the parsley. Reduce until you have a coating consistency, but don’t allow the sauce to go syrupy. Mix well and check the seasoning, then pour the contents of the pan over the chicken. Serve immediately with rice.