1. Heat the oil in a large skillet, fry the lamb for 2-3 minutes each side or according to taste. Remove from the pan and keep warm.
2. Lower the heat and add the port to the pan juices with the black currants and sugar. Cook for 2-3 minutes until syrupy.
3. Stir in the cheese, allowing it to melt in the heat of the sauce and serve over the lamb.