Make the special sauce first by mixing mayo, ketchup, mustard, diced pickles, pickle juice, garlic powder, and black pepper in a bowl. Chill while cooking.

Portion ground beef into 2 to 3 ounce balls, being careful not to overwork the meat.

Slice the onion thin for grilling on the patty and set aside a portion for crispy onions.

Heat a cast iron skillet or heavy pan on medium high to high heat until hot.

Toast the buns in the same pan with a little butter, then set aside.

Place a meat ball in the pan, top with thin onions, and press down hard with a spatula.

Cook for 60 to 90 seconds without moving, then flip after crispy edges form.

Add cheese on top immediately after flipping, then cook for another 45 to 60 seconds.

Spread special sauce on the bottom half of each toasted bun.

Stack the cooked patties on the buns and add pickles and crispy onions on top.

Place the top half of the bun and serve immediately.