PREHEAT OVEN TO 325F. Heat the olive oil over medium heat in a heavy roasting pan or Dutch oven large enough to hold the shanks in 1 layer on the stove. Add the shanks and cook 10 minutes on each side. Pour off all but 2 tablespoons fat; add the onion, carrot and celery and cook 5 minutes. Add the garlic, wine, water, lemon, salt and pepper. Cover and place in the oven. Cook 1 1/2 hours or until tender. Turn the lamb every 30 minutes and check to ensure that the liquid has not evaporated. If the pan is dry, add another cup of water. When lamb is tender, remove the shanks from the sauce, strain the sauce through a fine sieve and discard the vegetables. Skim and discard fat from the surface of the braising liquid. To serve, arrange the shanks on a platter and serve the braising liquid on the side.