If you're down in the Sooner State and order a burger, you're going to get one heckuva taste treat....The Oklahoma Fried Onion Burger. It's essentially a smash burger with paper-thin fried onions pressed into the burger on one side. This burger was created by Ross Davis in 1926. He ran the Hamburger Inn on Route 66 in El Reno, Oklahoma.
There are 3 critical ingredients to making this burger. The first is the onion. You want a sweet yellow onion sliced really thin on a mandolin. Then you salt the slices and let them drain. If you don't do this step, your onions will have too much moisture and will steam instead of frying. Second is the beef. You want a minimum of 15% fat (85% lean). Fat is flavor and you want that fat to give you a really good char on the non-onion side of the patty. Third is the bun. Sorry....only a soft and fluffy potato bun will do.
- Combine onion and 1 teaspoon salt in bowl and toss to combine. Transfer to colander and let sit for 30 minutes, tossing occasionally. Using tongs, transfer onion to clean dish towel, gather edges and squeeze onion dry. Sprinkle with ½ teaspoon pepper.
- Divide onion mixture into 4 separate mounds on rimmed baking sheet. Form beef into 4 lightly packed balls and season with salt and pepper. Place beef balls on top of onion mounds and flatten beef firmly so onion adheres and patties measure 4 inches in diameter.
- Melt butter with oil in 12-inch nonstick skillet over medium heat. Using spatula, transfer patties to skillet, onion side down, and cook until onion is deep golden brown and beginning to crisp around edges, 6 to 8 minutes. Flip burgers, increase heat to high, and cook until well browned on second side, about 2 minutes. Place 1 slice cheese on each bottom bun. Place burgers on buns, add desired toppings and serve.