For sauce, dice pickle very fine and stir ingredients together. Store in refrigerator until needed.
Portion out three 6-oz. burgers and roll them into loose balls.
Heat your large cast iron skillet over medium-high heat for a few minutes until it’s very hot. While it’s heating prepare the second cast iron skillet (smaller) and wrap some foil around the bottom of it.
When you’re ready to cook a burger, add some butter to the hot pan and let it melt. Then add a burger ball and press it down hard with the second skillet. Try to press down straight from above so create an even circle. Press down on the burger for 10 long seconds.
Remove the top skillet and season the burger with seasoning mix. When the juices start to bubble up from the burger, flip it.
If you’re adding cheese, add it after the flip and cover the burger with a metal bowl to steam the cheese.
Cook the burger on the second side until the burger reaches 165 degrees F. in the center, about 90 seconds or so.
Serve the burger on a toasted bun with lots of sauce, lettuce, tomatoes, and red onion.