1. Combine the lemon and orange juice, soy sauce, tomato paste, garlic, oregano, parsley, salt and a few grindings of black pepper in a large, shallow baking dish. Stir until all the ingredients are well combined. Place the swordfish in the dish, baste thoroughly and marinate for about 2 hours at room temperature, turning the fish over after the first hour.
2. Preheat the broiler to its highest point for at least 10 minutes. Then, with a pastry brush, grease the broiler rack with the tablespoon of soft butter. Lay the swordfish on the rack, brush heavily with the marinade and broil the fish 3 inches from the heat for about 5 minutes, brushing it once or twice with the marinade.
3. When the surface of the fish is lightly browned, turn it over with a large spatula and broil on the other side for 5 minutes, brushing on the remaining marinade once or twice more to keep the surface of the fish well moistened.
4. When the swordfish is done it should be a golden brown and firm to the touch. Be careful not to overcook. Transfer the fish to a heated platter, pour the broiling pan juices over it and serve at once, cut into appropriate portions.
