Peel and very thinly slice the red onion.
Mince the pickles, and finely slice the lettuce.
Place the mayonnaise, ketchup, and mustard in a mixing bowl. Season with a pinch of Rancher’s Steak Seasoning and set aside. This is the smash burger sauce.
Heat the cast iron pan over medium low heat. Add the butter to the pan and allow it to get nice and foamy. Toast the buns until golden brown and delicious.
Wipe the pan clean and heat over high heat.
Season the smash burgers on all sides with Rancher’s Steak Seasoning.
Add the oil to the pan and heat until lightly smoking.
Add the smash burgers to the pan and press until flattened. Cook on one side until well browned.
Flip the burgers and top with the cheese. Cover the pan so the cheese gets nice and melted.
Dress the buns with the smash burger sauce; top the sauce on both sides with minced pickles.
Transfer the smash burgers to the buns and top with the thinly sliced red onion and romaine lettuce. Dig in and enjoy a delicious smash burger!!