Knife the lamb meat, making a stew. Heat the oil in a large frying pan with two cloves of garlic and the rosemary and add the meat. Brown the meat for a few minutes until golden brown and deglaze with a glass of white wine. Let all the liquid evaporate, cover the pot and let it cook for about an hour, adding water or stock if necessary. Now remove the lid and leave for another 20 minutes or until the cooking liquid has evaporated. The meat should be tender and well browned. At the end of the cooking time, add grated or flaked black truffle.