Trim fat from meat. In a small bowl stir together mustard, rosemary, garlic, and pepper; brush onto meat. Toss together bread crumbs and nuts. Gently press the crumb mixture onto the roasts on all sides.
Place roasts on a rack in a shallow roasting pan. Insert a meat thermometer into the center of the meat without touching bone. Roast in a 325 degree F oven until desired doneness. Allow 45 minutes to 1 hour for medium-rare (140 degree F) or 1 to 1 1/2 hours for medium (155 degree F).