01 -
Form ground beef into 4 equal patties. Season each side with salt and black pepper.
02 -
Preheat a skillet over medium heat. Cook patties for approximately 4 minutes per side until fully cooked.
03 -
While patties cook, combine mayonnaise, ketchup, mustard, and chopped pickles in a bowl. Stir until smooth.
04 -
Spread butter on one side of each slice of rye bread.
05 -
Place a cooked patty on the unbuttered side of a rye slice. Top with caramelized onions, a slice of Swiss cheese, then another slice of bread with buttered side facing out.
06 -
Place assembled sandwiches in the skillet, buttered side down. Cook until golden brown, then flip and cook the other side until golden and cheese melts.
07 -
Remove sandwiches from skillet and serve alongside the secret sauce.