EVOO – Extra Virgin Olive Oil
3 large onions, cut in half and thinly sliced
Salt and pepper
1 1/2 pounds 70-80% lean ground beef
8 slices Comté cheese
4 Kaiser rolls, split
12 to 14 cornichons, finely chopped
Heat a skillet over medium heat with olive oil, 2 turns of the pan. Add onions and season with salt and a little pepper. Cook onions until caramel in color and very sweet, 35-40 minutes.
Heat a cast-iron skillet or griddle over medium-high heat. Loosely form 4 patties of beef and place them onto a hot grill, flattening them evenly with a spatula. Season with Kosher salt and pepper, top with caramelized onions and press onions into the burger. Cook to crust and brown the meat, 3 minutes. Flip, season and press and crisp the opposite side; cook 2-3 minutes more.
Butter the insides of the Kaiser rolls. Layer your burgers: Kaiser roll bottom, butter-side facing out, cornichons, cheese, burger patty, cheese, Kaiser roll top, butter-side facing out.
Return the built burgers to your skillet or griddle, and press them down with a pot lid or a heavy pan to brown the rolls and melt the cheese. Once brown on one side, flip and press them down again to brown other side.