The concept for cooking burgers this way came from Joe's Onion Burgers (now long gone) in Oklahoma City. I ate there quite a few times and the entertainment was watching him grab a ball of meat, wad it up, and slam it on the big, hot griddle. Right after that, he'd reach in a big tub and grab a handful of thinly sliced onions and toss them on, followed by a squirt of oil. Once they were translucent, he'd flip the burger "smash" and pile the onions on top for a minute or so, then it went to the bun, grilled with butter. You could get pickles, mustard, lettuce, mayo or a few other things on the burgers but most folks just ate them as meat, onions, and bread. They didn't really need anything else. I miss Joe's!
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