Gently divide the ground beef into 4 equal portions (4 oz each) and loosely roll them into balls. Do not overwork the meat. Place them on a parchment-lined plate and refrigerate until ready to cook.
Prepare all your toppings: wash and dry lettuce, slice tomato and onion, and have your cheese, pickles, and sauce ready.
Place a cast-iron skillet or griddle over medium-high to high heat and let it preheat for 5-7 minutes until it is extremely hot. Add a thin layer of oil just before cooking.
Place one or two beef balls onto the hot surface. Immediately use a sturdy spatula to press down firmly until the patty is about ¼ inch thick. Hold for 10 seconds to create a flat surface. Season the top generously with salt and pepper.
Cook for 60-90 seconds, until the edges are brown and crispy. Use the spatula to scrape cleanly under the patty, ensuring you lift the entire crust, and flip it over.
Immediately place a slice of cheese on top of the flipped patty. Cook for another 30-60 seconds until the cheese is perfectly melted.
Remove the patty from the skillet. Assemble your burger by placing one or two patties on a lettuce leaf, then top with sliced onion, tomato, pickles, and a drizzle of keto-friendly sauce.