Combine Hellmann's® or Best Foods® Real Mayonnaise, ketchup, mustard, molasses and horseradish in small bowl. Season, if desired, with salt and black pepper. Cover and refrigerate at least 30 minutes.
Heat grill pan or grill on high heat. Brush steak with oil on both sides and season, if desired, with salt and black pepper. Grill, turning once, 8 minutes or until desired doneness. Let stand 5 minutes, then thinly slice.
Spread mayonnaise mixture on rolls. Arrange steak on rolls, then top with lettuce.