In large, deep skillet, or dutch oven, melt butter.
Add sliced onion (and green pepper if using) and cook just until they start to sweat.
Add mushrooms and frozen steak strips.
Add your seasonings (season salt, garlic powder, black pepper).
Keep heat on about medium to medium high (you are going to cook these pretty fast).
Stir occasionally to ensure all meat is browning.
While meat is browning, open rolls, place on cookie sheet, and"toast" in oven.
Cook meat mixture until all meat is brown.
(Tip: Just as meat is done, I will"recheck" seasoning, and usually end up having to add a little more) Spread each roll with generous amount of meat mixture and top each sandwich with mozzerella cheese.
Return to oven and broil just until cheese starts to brown.
Now hurry up and get back to that chair-- half time is almost over!