The daring simplicity of this recipe provides a platform for the lamb to shine in all its divine glory.
Preheat the oven to 500 degrees. Strip most of the surface fat from the lamb. (Your butcher may already have done this.) Cut between the ribs, almost down to the meaty eye. Divide each rack in half down the middle, sprinkle with salt and pepper and place in a roasting pan.
Roast for 15 minutes, then insert a meat thermometer straight in from one end into the meatiest part. If it reads 125 degrees or more, remove the lamb immediately. If it reads 120 degrees or less, put the lamb back for about 5 minutes, no more. Remove and let sit for 5 minutes; this will give you medium- to medium-rare lamb on the outer ribs, medium rare-to-rare in the center. Cook a little longer for more doneness. Serve, separating the ribs, if desired, by cutting down straight through them.
If you want to try to improve on perfection, rub a teaspoon or more of your favorite spice into the flat, fleshy side of the rack before roasting. Or rub it with a mixture of two tablespoons of olive oil, a clove of minced garlic, a cup of bread crumbs and about half a cup of fresh parsley. You can also make a quick sauce by removing the lamb from the pan to a warm platter, pouring off all but a tablespoon of fat and setting the pan over high heat. Add a cup of good red wine or port and cook, stirring and scraping, until the liquid is reduced to about a third of a cup. Stir in any liquid that has accumulated around the lamb, season to taste and spoon over the meat.