1. In large open roasting pan, place roast, fat side up. Insert meat thermometer into center of roast, being careful that pointed end of thermometer does not touch bone or fat. Roast meat in 325°F. oven until thermometer reaches 140°F. for rare (about 20 minutes per pound) or until of desired doneness.
2. About 40 minutes before roast is done, prepare coating: Into small bowl, tear bread into small pieces; stir in mayonnaise, parsley, green onion, mustard, lemon juice, and salt. Remove roast from oven; evenly spread mayonnaise mixture on top of roast. Roast 25 minutes longer or until coating is golden and roast is of desired doneness.
3. When roast is done, place on warm large platter and let stand at room temperature 20 to 30 minutes for easier carving. Reserve drippings. Prepare Yorkshire Pudding.
4. To serve, cut Yorkshire Pudding into serving pieces; arange pudding on platter with roast.