We made these on a small griddle we put on our gas grill outside. I think the griddle is key because it allows the fat rendered from the burger to fry the outside, and it is very hot but unlike cooking over flame won’t ignite and char the burger. Very key. Now I want a bigger griddle. Of course one could do this inside as well, but it would make the kitchen smell greasy.
- Loosely shape ~1/4 lb of ground beef into balls without over-working the meat. The original recipe says 30% fat, but burgers made with 16 or 20% (?) were good. Season with salt and pepper.
- Slice some onions into very thin slices.
- Heat a cast iron griddle until very hot (on the stove or the grill outside).
- Place balls of meat on the griddle for 30 seconds to 1 minute.
- Use a stout spatula to smash the balls into patties ~1/3-1/2 inch thick and cook for about 2 minutes.
- Gently press a handful of the thinly-sliced onions onto the burgers, then flip over so the onions are on the bottom. Cook for another 2 minutes.
- Top with cheddar cheese, cover, and cook for another 2-3 minutes.
- Serve on a tasty bun with your choice of condiments.