Preheat oven to 350 degrees.
Slice the onion and green peppers. Put over medium heat, spray pan generously with a low calorie butter sub like Pam. Begin to saute onions and peppers.
Slice the seitan into very thin slices. Try to get them all approximately the same size. Spray a pan generously with Pam and place the Seitan in flat. Try not to overlap slices too much. Put over medium heat. Cook for about 10 minutes until the Seitan is well browned and a little crispy.
While you're cooking that, add the mushrooms to the onions and peppers. Use Pam as needed.
Slice rolls in half. Each roll gets one slice of cheese halved, so some cheese goes on each slice of roll. Place the cooked Seitan in the rolls and top with sauted mushrooms, onions, and peppers. Arrange on baking pan so the rolls are all kind of standing up by leaning them against one another. Bake approximately 5 minutes or until slightly toasted and the cheese is melted.
Serve and Enjoy!