Combine the mayonnaise and horseradish in a small bowl. Spread the mixture on the cut side of each bun. Set a lettuce leaf on the bottom part of each bun. Divide and top the lettuce with cheese, beef, bell pepper, cucumber, sprouts and tomatoes. Secure the top buns in place. Slice each bunwich widthwise and serve.
Note: Sliced Swiss and cheddar cheese is available for purchase from our deli department showcase.