How to Make It
Light a grill. In a large bowl, mix the ground beef with the shredded Gouda. Form into 4 patties.
Thread the onion slices onto double bamboo skewers. Alternatively, thread the slices onto pairs of metal skewers. Brush the onion slices with oil and season with salt and pepper. Grill the onion slices over a hot fire until nicely charred, about 3 minutes per side.
Season the patties on both sides with salt and pepper and grill for 4 minutes per side for medium-rare. Top the patties with the sliced cheese, cover and grill until the cheese is melted, about 2 minutes. Butter the buns and grill cut sides down until toasted, about 10 seconds.
Place a few lettuce leaves and 2 tomato slices each on half of the buns and set the cheeseburgers on top. Cover with the grilled onion slices and top with some of the Pickled Grilled Peppers. Close the burgers and serve right away, with the remaining pickled peppers on the side.