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Delicious Onion Burger with Caramelized Onions, Beef Patty, and Cheese.

Onion Burgers

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  • Author: María
  • Total Time: 25 minutes
  • Yield: 8 burgers 1x


My idea of The Perfect Burger.


Units Scale

The Smashed Patties:

  • 2 lbs lean ground beef
  • 2 large Vidalia onions, sliced thinly
  • 1 tbsp salted butter
  • 1 1/2 tsp seasoned salt, to taste
  • 1 tsp vegetable oil
  • 1/2 tsp cracked black pepper
  • 1/2 tsp garlic powder
  • 1/4 tsp granulated sugar
  • 1/4 tsp cayenne pepper, optional

The Burgers:

  • 8 King’s Hawaiian Hamburger Buns, toasted
  • 8 slices american cheese
  • 3 tbsp mayonnaise*


  1. Place a 12″ cast-iron skillet over medium-high heat and allow it to preheat for 2 minutes. While it’s preheating toss together the sliced onions and granulated sugar in a small bowl.
  2. After 2 minutes add the vegetable oil and butter to the pan. Once the butter has melted add the onions to the pan and stir around to coat in the melted butter and oil. Spread into an even layer and reduce the heat to medium. Allow the onions to cook, stirring occasionally, until they are completely softened and browned, and starting to char a bit around the edges –  about 10-15 minutes.
  3. While the onions are cooking add the ground beef to a mixing bowl. Sprinkle in the seasoned salt, cracked black pepper, garlic powder, and cayenne pepper (if using). Stir together with a wooden spoon to distribute the seasonings evenly. Separate the meat mixture into 8 evenly sized portions and roll them into balls between your palms, pressing them together only slightly.
  4. Once the onions are nicely browned and starting to carmelize either remove them from the pan or shove them to the side. If you decide to keep them in the pan you’ll need to stir them ever so often to make sure they don’t burn. I recommend removing them if this is your first time making these.
  5. Increase the heat to medium-high and arrange your desired amount of onions in the center of the pan – I usually do a heaping dinner spoonful – and place one of the balls on top of them. Using a heavy metal turner – or your sturdiest spatula – and wooden spoon press down evenly on the meat so that it smashes down into a patty, as flat as you can get it (or as you like). You’ll use the wooden spoon to push down on the top of the metal turner to apply more pressure than you would normally be able to.
  6. Let the patty cook undisturbed for 4 minutes, then use the metal turner to scrape the onion patty up off of the surface and flip. Give it another smash to flatten further and secure the onions into the patty and allow to cook for another 3-4 minutes, or until they reach your desired temperature inside. While they’re cooking go ahead and spread the mayo on the burger buns.
  7. If you’re adding cheese, add it to the patty 1 minute after you flip it and cover the pan with a lid to encourage it to melt completely. Once it’s melted place the top of your hamburger bun on it, then lift the burger out of the pan, allow the excess grease to drip off, and transfer it directly to the bottom bun. Serve immediately, or place on a baking sheet in a 175°F oven to keep warm until you’re ready to eat. Dassit!


  • Not a fan of mayo? Sub whatever you like. I’m a Miracle Whip fan, myself. Read the post above the recipe for my thoughts on substituting the other ingredients.
  • Prep Time: 10
  • Cook Time: 15
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