Heat a pan and brown the swordfish in a knob of butter. Once the escalopes are cooked through, pour in the rum and flambé. Keep warm. Peel the combavas and sauté the zest for 1 minute. Deglaze the pan with the double cream to remove the juices. Bring the sauce to the boil for about 1 minute. Season with salt and pepper to taste. Drizzle the combava sauce over the escalopes and serve with rice, mushrooms and broccoli.