Boost the flavor on this lean beef roast with a classic thyme and mustard crust. To further complement this roast, add Dijon-style mustard to sour cream for a creamy sauce.
Preheat oven to 325°F. Combine 1/4 cup mustard, 1 tablespoon thyme and pepper. Spread mustard mixture evenly over all surfaces of beef Roast.
Place roast on rack in shallow roasting pan. Insert ovenproof meat thermometer so tip is centered in thickest part of beef. Do not add water or cover. Roast in 325°F oven 1-1/4 to 1-3/4 hours for medium rare doneness.
Meanwhile, combine remaining 3 tablespoons mustard and sour cream in small bowl; set aside. Heat oil in small saucepan over medium-low heat until hot. Add shallots and remaining 1 tablespoon thyme. Cook and stir 4 to 5 minutes or until shallots are tender and begin to turn golden. Remove from heat; stir into mustard mixture. Season with salt, as desired.
Remove roast when meat thermometer registers 135°F for medium rare. Transfer roast to carving board; tent loosely with aluminum foil. Let stand 20 minutes. (Temperature will continue to rise about 10°F to reach 145°F for medium rare.)
Carve roast into thin slices. Season with salt, as desired. Serve with mustard mixture.