I love very spicy and hot foods. When I have a sandwich, I substitute cheese with a Southwestern Mustard or Jalepeno mustard.
With the mustard's big taste, I wouldn't fully taste the cheese. I've eliminated calories and added flavor!
I always thought that it wasn't a sandwich unless it had cheese. This was one of the many habits I had to break. Using spicy condiments made this an easy one to break. Now when I do eat cheese, I like to eat it by itself so I can fully savor the flavor.