Trim excess fat off meat and score any remaining fat so heat can penetrate. Liberally salt and pepper meat all over. Insert a meat thermometer in the thickest part of meat, not touching bone. Put the onion, celery and water in a heavy, lidded casserole and place the roast on top, fat side up. About 2 1/2 hours before serving, for well done or when temp reaches 170 degrees, put roast in a preheated 375 degree oven. MEdium lamb is 160 degrees and rare is 140 degrees. A sirloin or shank roast will take about 30 minutes per pound for well done. For a saddle or rack, about 20 minutes per pound. Check on roast 2-3 times during cooking, adding water is needed and degreasing pan juices. When the meat is tender, combine bread crumbs, parsley, garlic and butter. Press crumbs over top surface of roast and return to oven in a shallow pan to brown about 10 minutes. Slice meat after letting it stand 5 minutes in a warm place. Use bread crumbs that fall off for garnish. Meanwhile, remove all the fat from the pan juices and strain juices. Reheat the sauce and serve in hot sauce boat along with sliced meat, garnished with sprigs of parsley and slices of sauteed pineapple.