Preheat a non-stick pan over low-medium heat.
Add the oil and onions to a saucepan on medium heat, cover with a lid. Let the onions cook, stirring occasionally until they become soft and golden brown (if the onions get too dark add a tablespoon or two of water this will smooth out the coloring). Once caramelized set aside.
In the meantime, mix together the ground beef, steak seasoning, garlic powder, and Worcestershire sauce. Season with salt and pepper, and form into oblong patties to fit the shape of the bread.
Heat a non-stick pan over medium heat. Cook the burgers on both sides to your desired doneness (see below) using a thermometer. Then remove from the pan and set aside. Do not discard the grease from the burgers.
Place the cheese on each slice of bread, layer with the burger, onions, and the other slice of bread on top.
In a non-stick pan over medium heat, using the reserved grease from the burgers, cover with a lid and cook the sandwich on both sides until golden brown while melting the cheese (if making multiple sandwiches use more oil as needed). Cut in half and serve with pickles and chips. Serve with ketchup or your favorite condiments.