Flat Burger Sliders

Flat slider burgers with onions on white plate with pickles and french fries

Flat Burger Sliders were created because, as you can only guess, there is no restaurant around here that serves decent thin patty burgers on slider buns.  In addition, there is no White Castle or Krystal Burger within easy driving distance of Tulsa.

I have seen the several hundred, maybe even thousands, of White Castle copycat recipes on the interwebs.  Yes, I have tried a few.  No they did not make me happy.

This recipe is not supposed to be a copycat of either of those restaurants.  I don’t believe you can accurately copy those recipes without their preformed patties, who knows what unhealthy additives, nor their large griddles.  I think there might even be some magic in the little boxes they stuff the baby burgers into.


Instead, this is just a method for cooking sliders at home that we seem to like pretty well.  The secret to getting the onions cooked perfectly without burning the burger is to salt them liberally before making the burgers.

Now before you get all worried about high blood pressure and salt consumption, the salt will just draw out moisture from the onions.  Most of the salt will be in the bottom of the bowl.  But if you like, go ahead and rinse the onions off before adding them to your burgers.

You also need a pretty sturdy spatula for this.  Trust me, I have broken more than a few before I finally broke down and went to the local restaurant supply house and bought a heavy duty one.  Alternately, you can roll the meat thin between pieces of wax paper.  But, I’m lazy and that’s just too much work for a burger.


Flat Burger Sliders

Flat Burger Sliders, thin burgers with perfectly softened and grilled onions. Ideal for small snacks and game day food spreads.

  • Author: Beth Mueller
  • Prep Time: 1 hour
  • Cook Time: 15 minutes
  • Total Time: 1 hour 15 minutes
  • Yield: 12 Sliders
  • Category: Appetizer
  • Method: Stovetop
  • Cuisine: Burgers


  • 1 large onion, sliced thinly
  • 2 teaspoons Salt
  • 1 1/2 pounds ground beef, 73/27 or 80/20 mix
  • 12 Hamburger Slider Buns
  • Cheese slices, optional
  • Pickle Slices, optional
  • Mustard, optional


  1. Place onion slices in a small bowl and cover with salt.
  2. Mix the onions and salt well, separating the onions into rings, and set aside for at an hour.
  3. For quicker assembly, separate buns and place them together with the middle of the bottom bun facing down, and the middle of the top half touching the brown bottom of the bun.
  4. Form meat into equal size balls and place on a plate near your griddle.
  5. Squeeze onions to remove any remaining liquid. Dump salty liquid from the bowl. Rinse the onions if desired, just make sure to squeeze them once more to remove excess water. I do not rinse.
  6. Set electric griddle to high and allow griddle to get very hot. If using a skillet, use medium high heat and preheat skillet.
  7. Once griddle is screaming hot, add 4 to 6 burger balls spaced about 4 inches apart on griddle. Top meat with onions.
  8. Let meat and onions sit for about a minute on the hot griddle.
  9. Smash the burgers as flat as possible with a spatula. This is where a sturdy spatula comes in handy. You want the burger thin so they cook rather quickly.
  10. Once the burgers look like they are mostly cooked through, flip them over.
  11. Cover each burger with one bun, inside of the bottom half touching the burger, inside of top half touching the bottom of the bottom half.
  12. Cover with an inverted cake pan or large lid.
  13. Cook burgers for another 2 minutes.
  14. Carefully remove the cake pan or lid. Use kitchen tongs if necessary, this covering will be very hot.
  15. Slide spatula under the burger and onions.
  16. Carefully remove the top half of the bun and place it under the spatula and slide the burger with the bottom half of the bun onto the top bun.
  17. Place on a plate and quickly cover with mustard and pickles. Add cheese now if using.
  18. Eat while hot.


  • Serving Size: 1 Slider
  • Calories: 252
  • Sugar: 1.5 g
  • Sodium: 611 mg
  • Fat: 11.3 g
  • Saturated Fat: 4.2 g
  • Carbohydrates: 17.2 g
  • Fiber: 1.3 g
  • Protein: 18 g
  • Cholesterol: 50 mg

Other Sandwich Recipes to Try:

Egg Bagel Sandwiches

Patty Melt

Bon-A-Part Open Face Burger

Italian Beef


Flat Burger Sliders with onions cooked into the meat are perfect for entertaining a crod. Try them at your next tailgate or game day party.

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