Lightly mix 6 ounces ground beef chuck with a big pinch of kosher salt. Form into three, 2-ounce balls, then into 3/4-inch-thick patties; make an indentation in the centers.
Heat a cast-iron skillet over medium-high heat; sprinkle the skillet with salt. Cook the burgers 3 minutes per side. Top with Swiss in the last minute of cooking (cover to melt). Serve on mini potato buns with pickles and ketchup.