Top juicy burgers with a tart cornichon relish that goes well with creamy Comté.
Stir together the cornichon, shallots, and oil in a small bowl.
Form the beef into 2 equal patties, about 4 inches wide and ½-inch thick, and create a depression in the center of each patty.
Heat a large cast-iron skillet over medium-high heat until just smoking. Sprinkle the patties generously with salt and pepper. Put the patties in the pan with the depression facing up. Cook until the bottom gets brown and crusty, about 4 minutes.
Flip and place the cheese on top. Continue cooking to your desired doneness, 3 to 4 minutes more for medium-rare.
Divide the cornichon relish on the bottom buns. Place a burger on top. Put a slice of tomato and lettuce on the burger, and top with the bun.