Make the sauce. Whisk all sauce ingredients together and refrigerate while you cook.
Shape the patties. Divide the beef into 8 portions (about 2 ounces each), press into thin 1/4-inch rounds, and season with salt and pepper.
Cook the patties using your preferred method:
Air fryer: 375°F for 5 to 7 minutes, flipping halfway.
Blackstone: medium-high for 2 to 3 minutes, flip, then 1 to 2 minutes more.
Skillet: medium-high for 2 to 3 minutes per side.
Oven: 375°F for 10 to 12 minutes, flipping halfway.
Grill: high heat for about 2 minutes per side.
Melt the cheese. Add cheese to 4 of the patties during the last minute of cooking.
Toast the buns until lightly golden.
Assemble. Bottom bun, sauce, lettuce, cheese patty, middle bun, sauce, lettuce, onions, pickles, second patty, top bun.