Fried Onion Smash Burger

A fried onion smash burger is what happens when a thin, crispy-edged beef patty meets a pile of onions cooked right into the burger. The beef gets smashed onto a screaming hot griddle, the onions soften and brown beside it, and everything finishes with melted cheese and a toasted bun.

The trick is not just throwing onions on a burger at the end. For the best smash burger with onions, the onions need to be sliced thin, salted ahead of time, and cooked hot enough to lose their raw bite while the burger gets that crusty griddle edge. It is messy in the best way, fast once the prep is done, and a lot better than a thick backyard burger pretending it can do the same job. I love using my Blackstone for these burgers; they do great on a large flat surface.

What Makes an Onion Smash Burger Different?

A regular burger is shaped into a patty before it hits the grill. A smash burger starts as a loose ball of ground beef that gets pressed hard onto a hot griddle. That extra contact with the heat creates the browned, crispy crust that makes smash burgers worth making.

For an onion smash burger, the onions are part of the cooking process, not just a topping. They cook on the griddle with the beef, picking up salt, beef drippings, and browned bits from the surface. The result is a burger with crispy edges, softened onions, melted cheese, and a lot more texture than a standard cheeseburger.

The Best Onions for Smash Burgers

Use a large yellow onion or white onion and slice it very thin into half-moon pieces. Thin slices cook faster and are easier to tuck into the burger without turning into a slippery pile.

The important step is salting the onions before cooking. Salt draws out moisture, which helps the onions brown faster on the griddle instead of steaming. After the onions sit, drain off the liquid and blot them dry before cooking. This one small step makes a difference. Wet onions will fight you. Drier onions will brown.

Ingredients You’ll Need

• Ground beef: Use 80/20 ground beef. Lean beef does not give you the same crust or juicy center.
• Onion: A large yellow or white onion works best. Slice it thin so it cooks quickly.
• Salt: Used to draw moisture from the onions and season the burger.
• Pepper: Add directly to the patties once they are smashed.
• Oil: A little oil helps the onions cook and keeps the griddle surface working with you.
• Cheese: American cheese melts best for a classic smash burger. Cheddar works, but it does not melt as smoothly.
• Hamburger buns: Toast them on the griddle before assembling.
• Condiments: Pickles, mustard, ketchup, mayo, burger sauce, or whatever you like. Do not overthink it.

How to Make Fried Onion Smash Burgers

Start by slicing the onion into very thin half-moons. Add the onions to a bowl, sprinkle with salt, stir, cover, and refrigerate for 1 hour. Drain off the liquid, then blot the onions dry with a paper towel.

Divide the ground beef into 4 loose balls. Do not overwork the meat. Loose beef smashes better and gives you those rough edges that crisp up on the griddle.

Heat a large flat top griddle until very hot. Add a little oil, then place the onions on the griddle. Add the beef balls nearby, place a square of parchment paper over each one, and smash firmly with a heavy spatula, burger press, or small cast iron skillet. Peel off the parchment paper.

Season the patties with salt and pepper. Cook until the edges are browned and crisp, then scrape firmly under each patty and flip. Flip the onions as needed, then pile some onions on each patty and top with cheese.

Toast the buns on the griddle, then build the burgers while everything is hot.

Tips for the Best Onion Smash Burgers

A smash burger is not complicated, but the little details matter. The difference between a crisp, browned onion smash burger and a soft, steamed burger usually comes down to moisture, heat, and timing.

Salt the onions first

Thinly sliced onions release a lot of moisture. Salting them ahead of time pulls out some of that water so they can brown faster on the griddle instead of steaming. After they sit, drain them well and blot them dry before cooking.

Use a very hot flat surface

A Blackstone, flat top, or large griddle works best because the beef and onions need space. A skillet can work for one or two burgers, but it gets crowded quickly. If the surface is not hot enough, the patties will cook, but they will not get that crisp smash burger crust.

Smash once, then leave it alone

Place the beef ball on the hot griddle, cover it with parchment paper, and smash it firmly right away. After that, do not keep pressing it. Let the burger cook undisturbed so the crust can form.

Scrape under the patty when flipping

Do not gently lift the burger like a regular patty. Use a thin metal spatula and scrape firmly under the burger so the browned crust stays attached to the meat instead of sticking to the griddle.

Use parchment paper

This is the easiest way to keep the beef from sticking to your spatula, press, or cast iron pan. Put the parchment over the beef ball, smash hard, then peel it off. The first time I tried this without parchment and it stuck badly.

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Smash Burger FAQs

What onions are best for smash burgers?

Yellow onions or white onions work best. Slice them very thin so they cook quickly and blend into the burger instead of sitting on top in thick pieces.

Can I make onion smash burgers in a skillet?

Yes, but a large griddle or flat top works better. A skillet can get crowded, especially when cooking the onions and multiple patties at the same time.

Why salt the onions before making smash burgers?

Salt pulls moisture out of the onions. This helps them brown faster on the griddle and keeps the burger from getting watery.

What kind of beef is best for smash burgers?

Use 80/20 ground beef. The fat helps create a better crust and keeps the thin patties juicy.

Do I smash the burger more than once?

No. Smash it once, right after it hits the hot griddle. Pressing again later pushes out juices and does not help the crust.

FRIED ONION SMASH BURGER RECIPE
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