Cut shallow slits all over roast; insert garlic slivers into slits. Rub all over with Worcestershire sauce, salt and pepper. Combine parsley, mustard, herbes de Provence and oil in bowl. Set aside 2 tbsp (30 mL) of the mixture for Shallot Gravy, rubbing remainder all over roast.

Place roast, bones down, on rack in shallow roasting pan. Insert oven-safe meat thermometer into centre of roast. Roast, uncovered, in 450°F (230°C) oven for 10 minutes. Reduce heat to 275°F (140°C); roast until thermometer reads 135°F (57°C) for medium-rare to medium, about 2-3/4 to 3-1/4 hours.

Remove from oven. Cover loosely with foil and let stand for 15 to 30 minutes before carving. Drain off all but 2 tbsp (30 mL) drippings from roasting pan and make Shallot Gravy.

Shallot Gravy: Place roasting pan over medium heat; add 3 shallots (coarsely chopped) and reserved herb rub. Cook, stirring until shallots soften. Stir in 2 cups (500 mL) beef broth and 3 tbsp (45 mL) Worcestershire sauce; simmer, stirring up any browned bits from bottom of pan. Combine 1 to 2 tbsp (15 to 30 mL) cornstarch with equal amounts cold water, making smooth mixture. Gradually stir into broth; bring to boil, stirring until thickened, about 3 minutes. Strain.