Trim and tie roast if desired. In a small bowl, combine the fennel seed, crushed rosemary, basil, marjoram, savory, thyme, and sage; rub over roast.
Place fat side up in a roasting pan. Top with onion and rosemary sprigs. Bake, uncovered, at 350°F for 2-3 hours or until meat reaches desired doneness (for medium-rare, a meat thermometer should read 145°F, medium 160°F, well-done 170°F).
Discard onion and rosemary. Let roast stand for 10-15 minutes before slicing. meanwhile, in a small bowl, combine the sauce ingredients. Serve with beef.