Preheat oven to 425° F.
Rub beef with oil and season with salt and pepper. Place in a flame-proof roasting pan and roast for 30 to 40 minutes or until meat reaches desired doneness (130° F for rare, 140° F for medium-rare). Remove meat from oven when temperature is 10° shy of desired doneness since roast will finish cooking as it rests.
Add shallot to roasting pan. Heat Drambuie in a small saucepan over low heat until warmed. Pour Drambuie over beef and quickly ignite, using a long match. When flame goes out, remove beef to a serving platter and hold, loosely covered.
Add flour to roasting pan and cook over medium heat, stirring constantly for 1 minute. Whisk in beef broth, mustard and Worcestershire sauce. Bring to a boil and whisk until smooth. Season to taste with salt and pepper. Transfer to gravy boat.
Slice beef and serve with sauce.Servings: 8