Thinly slice onion using a mandolin or a knife.
Form ground beef into 4oz balls.
Combine burger sauce ingredients.
Heat cast iron/stainless steel pan on medium high heat for 2-3 minutes. It's hot when water beads up.
Place balls on pan and season with salt and pepper.
Add a small handful of onions on top and smash down as hard as you can to make a thin patty.
Cook for two minutes, scrape and flip over.
Add cheese and buns(top bun first then bottom bun).
Once the cheese is melted(1-2 minutes), assemble burger with pickles and sauce.
