Add the ingredients for the special sauce to a bowl and whisk until smooth. Transfer to a small bowl or squeeze bottle and set aside.
Brush the buns (top and bottom) with butter. Warm a pan over medium heat. When warmed, add the buns, toasting them for about 1 to 2 minutes. Repeat until you’ve worked your way through all of the buns
Meat Options + To Grind and Form:
If you’re grinding your own meat, add the cubed sirloin and chuck to a bowl and combine it. With the largest meat grinder attachment on your mixer or grinder, turn the speed to #4 and add the meat. Repeat until you’ve worked your way through all of the meat. Change the grinder attachment to the smaller attachment. Pass the meat through the grinder once more. Divide the meat into 4 ounce mounds. You should end up with 8 mounds of meat.
If you’re using store-bought ground beef, no biggie. Divide the meat into 4 ounce mounds.
Form pucks that are about 2 inches tall and 2-inches wide. Sprinkle the tops with a few pinches of salt and pepper.
Place a cast iron skillet over moderately high heat. Add a few teaspoons of oil and when glistening and VERY hot, add the meat puck. Allow to cook for about 30 seconds and then smash it with a spatula until it’s about 1/4-inch thick. Cook for about 1 minute and then add a few pinches of salt and pepper to the top. Then, flip. Add the slice of cheese and cook for an additional minute or so. Remove from the pan and repeat with the remaining pucks of meat.
Squeeze a bit of special sauce on both sides of the bun. Add a few pieces of leafy green lettuce, a few slices of tomatoes and then top with the burger patty. Add a few pickles and then add the other half of the bun on top. Repeat until you’ve made all of the hamburgers.
Serve with baked crinkle fries, ketchup and mustard on the side.