Make a savory lamb gravy with the meat juices while the lamb is resting. Strain 3 cups of the pan juices (add beef stock if needed). Pour 1 cup meat juices into a medium sauce pan and add 1-2 tablespoons butter. Once it starts to simmer, whisk in 4 tablespoons of flour and cook for 1 minute. Stir in any remaining juices/stock and season to taste. Simmer until the gravy thickens.