Marinated Peppercorn and Mustard Beef with Horseradish Mayonnaise

FOR THE BEEF:
Preheat oven to 350 degrees F.

Tie the beef with string and place in a shallow dish. Add red wine, oil, garlic, bay leaves, and onion; leave to marinate for several hours. Pour off 2 cups of the marinade and discard. Place beef in the oven with remaining marinade and bake for about 1-1/4 hours or until cooked as desired. Allow to cool to room temperature, remove string and roll meat in cracked peppercorns.

FOR THE MAYONNAISE:
Combine all mayonnaise ingredients and mix well.

TO SERVE:
At serving time, slice beef and serve with mayonnaise.