1 (8 oz.) dairy sour cream
3 tbsp. Dijon mustard
2 tbsp. prepared horseradish
2 tbsp. whole green peppercorns
2 tbsp. whole red peppercorns
2 tsp. coarse salt
1 (4 to 4 1/2 lb.) beef tenderloin, trimmed
1 cup chopped fresh flat-leaf parsley
1/4 cup (1/2 stick) butter, softened
3 tbsp. Dijon mustard

Combine first 3 ingredients. Cover and chill.

Place peppercorns in container of an electric blender; cover and pulse until chopped. Place in a container and stir in salt. Place beef on a lightly greased rack in a shallow roasting pan. Combine parsley, butter and 3 tablespoons mustard and rub mixture evenly over the beef tenderloin. Pat peppercorn mixture evenly over beef.

Cover and chill up to 24 hours.

Bake at 350°F for 50 minutes or until meat thermometer inserted in thickest portion of beef registers 140°F (medium to rare) to 160°F (medium). When done, let stand for 10 minutes before slicing. Serve with cream mixture.