Prepare the Bread

1. With a serrated knife, slice the hero rolls 3/4 of the way through.
2. In a large skillet or grill pan, toast the buns. Remove from the equation.

Preparing the Filling

1. In a large nonstick skillet, heat the oil over medium high heat. Add the diced onions and cook until they are caramelized. Place the mixture in a bowl and put it aside.
2. Using salt and pepper, season the patties.
3. In the same skillet, increase the heat to high and add the burger patties. Cook for 4 minutes, or until the bottom of the pan is beautifully browned.
4. Cook for 1 minute after flipping the burger. Cut the burger into small pieces with two steel spatulas. Constantly stirring
5. Continue to chop and whisk in the cooked onions.
6. Divide the mixture into four equal portions and top each with two slices of cheese. Remove from the heat to allow the cheese to melt properly.

Assemble the Sandwich

1. On the hero roll, spread a thin coating of mayo. Pour ketchup on top.
2. Carefully transfer the contents into each roll using a sharp spatula.
3. On top of the filling, scatter sliced tomatoes and shredded iceberg lettuce. If desired, season with extra salt and pepper.
4. Wrap each roll in aluminum foil if desired. Serve warm, cut in half, and enjoy!