Cut slits into leg of lamb and insert slivers of garlic [to taste -- you can also add whole unpeeled cloves of garlic to the pan, once some drippings have formed in the pan].
Coat leg of lamb with oil.
Sprinkle with salt, pepper and fines herbes, patting these into the oil.
Bake 25 minutes per lb for rare, or longer for medium.
Remove and let sit for 20 minutes before serving --.
Remove excess fat from pan and make gravy with water and cornstarch (which has been dissolved in cold water and THEN added) to thicken.
For shepherd's pie leftovers: Trim meat off bone after dinner; cut into 1-2 inch cubes; grind in a food processor or blender; add chopped onion to taste; add enough gravy to bind and moisten [can use Knorr beef gravy mix in a packet or better than bouillon beef base].
Steam 1 potato per 1 cup of ground meat; mash with some milk, butter, salt and pepper to taste; put 1/3 of potato mixture into ground meat; pat into a casserole and top with remaining mashed potatoes; sprinkle with paprika and bake at 375°F until it's bubbling (about 30 minutes).