01 -
Using a mandolin, slice the onions as thinly as possible. Toss with kosher salt and allow to sit for 20 minutes. Squeeze out excess moisture before using.
02 -
While onions rest, divide ground beef into equal portions, approximately 110 grams (1/4 pound) each. Roll into balls and refrigerate for 15 minutes.
03 -
Preheat the griddle on high for 10 minutes. Lightly oil the surface as needed.
04 -
In a bowl, combine mayonnaise, ketchup, mustard, sweet relish, hot sauce, black pepper, and kosher salt. Whisk until smooth and set aside.
05 -
Place beef balls on hot griddle. Top each with a generous amount of prepared onions, then firmly smash down to achieve a thin patty. Season as desired.
06 -
Cook the patties for 4 minutes, then flip. Season the opposite side and after 2 minutes, lay a slice of American cheese over each patty. Position the top bun over the cheese and the bottom bun on top to steam. Close the lid and steam for several minutes.
07 -
Remove bottom buns from the top, spread with burger sauce, and layer with sliced pickles. Place a patty (or two) onto each bun and finish assembling. Serve immediately.