To begin, slice the onion and green bell pepper. In a large skillet, sauté the pepper and onions until desired tenderness. (I suggest you start the peppers first, as they take longer.)
While they cook, slice the cubed steaks into strips across the grain of the meat - about 1/2 inch wide. Season with the all purpose seasoning.
Remove the onion and pepper to a dish. In the same skillet, cook the meat (in batches so as to not crowd it) over high heat until it is just done and had good color on it.
Place all of the cooked meat, onion, and pepper back into the skillet.
Stir in the Worcestershire sauce and remaining butter.
When the butter is melted and everything is hot, prepare your bun with your toppings. (spread, cheese, etc) Place the hot meat on top of the cheese side.
Enjoy!
To Prepare the Sandwich Sauce:
Combine ingredients in a microwave safe bowl. Cook in high for 15 seconds. Stir until the cheese is melted and all is combined. Add a few more seconds if you need to. You can also prepare this in a small saucepan and stir over medium heat until melted together.