Slice the onion and slowly brown in 2 Tbsp of butter until onions are soft and carmelization begins, should be ready a little before the beef is done, sprinkle lightly with salt when done.
In a medium bowl, combine ketchup, cola, and Worcestershire and syrup.
In a sauce pan, bring to a boil and then simmer, uncovered, 20 minutes, stirring occasionally.
While the sauce is cooking, slice the round steak and chop the pepper.
In a 12 inch skillet on med-high setting heat the oil and add the chopped green pepper and cook for 2 mins (or until soft).and then add the sliced beef and garlic powder.
Quickly cook the meat just until no longer red and no blood is showing, you may need to do this in batches. If the sauce is ready add the meat and peppers to it right away. If not just set the skillet aside for the few mins until the sauce has cooked for the 20 minutes.
After the 20 mins add beef mix and gently simmer an additional 5 minutes.
Serve on toasted buns with onions topping the beef mix.