Quick and easy dish. First fry the lamb fillet brown on all sides. Then place the lamb fillet for 5 minutes in a pre heated oven (200°C). Cook the green beans for about 5 minutes. Cook the potatoes. Chop a red onion very fine and fry in the same pan you fried the lamb fillet. Add some tomato puree, and let it fry along for a few minutes. THen add the coconut milk and cook untill you got a smooth sauce. Stew the beans in butter. Let the lamb rest under alumium foil for about 5 minutes before slicing it. Serve hot.