In a saucepan boil the potatoes. Sirloin divide into two portions and seasoning with salt and pepper. In a pan with preheated oil fry the fillets in about 3 minutes on each side. Subtract a plate and fry the garlic in the oil for a few seconds, add the chopped tomatoes and fry 10th minutes, add salt, counterfeiting and add chopped olives and capers. Stir in baking dish and poured on the bottom part of the sauce, put it on the fillets and potatoes, peeled and cut, and pour on top with the remaining sauce. Bake in preheated 220 C oven for 25 minutes. Serve sliced ​​tenderloin diagonally with potatoes and pour the sauce.