Heat 1 tablespoon oil in a small pan, add the onion and cook for 5 minutes until softened. Add the ginger, plums, sugar, vinegar, orange rind and measurement water and simmer for 10 minutes until soft. Season to taste.
Meanwhile, rub the remaining oil over the chops and season. Cook under a hot grill for 5 minutes on each side until just cooked through. Serve with spoonfuls of the relish and some watercress.