Wash the lettuce leaves and prepare 8 healthy-looking leaves. Remove the Reblochon’s rind and cut it into cubes approximately 0.5cm across.
Heat the oil in a large frying pan and cook the burger patties for the time according to your taste. In the meantime, toast the hamburger buns. Spread the bread with a layer of mustard, then place a lettuce leaf and a thin slice of tomato on top of it, followed by the meat.
Cover with Reblochon slices, onion rings, and garnish with a second lettuce leaf, spread the top half with mustard and then close the burger.
Hold it all together with a wooden toothpick.
Serve immediately, while still hot, and eat with your hands!