Oklahoma Fried Onion Burger

Ingredients:

1 large onion, thinly sliced after being peeled and halved
Salt and pepper
1 pound of ground beef
1 tablespoon of butter
1 tablespoon of vegetable oil
4-8 slices of American cheese
Mayo, mustard, and pickles for serving
4 hamburger buns, toasted
Instructions for Making Oklahoma Fried Onion Burgers:

Start by combining the thinly sliced onions with 1 teaspoon of salt in a bowl and mix them together. Transfer the seasoned onions to a colander and let them sit for 30 minutes, stirring occasionally. Then, transfer the onions to a clean dish towel, gather the edges, and squeeze out as much liquid as possible from the onions. Make sure to do this over a sink or a large bowl, as the onions will release a significant amount of liquid.
Divide the drained onions into 4 separate piles on a rimmed baking sheet. Shape the ground beef into 4 gently packed balls. Place these beef balls on top of the onion mounds and press down firmly (using your palm) so that the onions adhere to the beef. The resulting patties should measure 4 inches in diameter. Season the beef generously with salt and pepper.
In a 12-inch skillet, melt the butter along with the vegetable oil over medium heat. With the help of a large spatula, carefully transfer the patties to the skillet with the onion side facing down. Cook them for 6-8 minutes until the onions become a deep golden brown and start to crisp around the edges. Flip the burgers, then increase the heat to high and cook for about 2 more minutes, or until well browned on the second side.
Add 1 or 2 slices of American cheese to each burger and allow it to melt. Meanwhile, spread mayo, mustard, and pickles on the top buns. Once the cheese has melted, place each burger on the bottom buns. Serve immediately.