Heat a saute pan and add the olive oil.
Heat the grill if using for the steaks.
Add the sliced onions and peppers to the heated saute pan and oil.
Cook until the onions are starting to turn translucent and the peppers are getting soft. Then add salt, pepper, and the 1 T of butter. Stir and cook until the butter is melted.
If using the grill put the meat on when you start the peppers and onions.
If using the saute pan to cook the steaks, remove the peppers and onions then put the steaks in the pan. Season with Lawry's salt on both sides.
Cook to your liking.
To assemble the sandwich, add a thin layer of mayo to the bun or bread. Put down a slice of steak, next put cheese on the meat, layer tomatoes, sauteed vegetables, and then top with the bun or bread.