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    Smash Burgers

    May 6, 2025 / By Natalie Mortimer

    Homemade smash burgers are a summertime staple! Those crispy-edged burger patties with cheese and homemade burger sauce oozing down the sides are fast, easy and impossible not to love.

    smash burger on a toasted bun, layered with crisp lettuce, cooked onion, melted American cheese, and a slice of fresh tomato
    Photography by Gayle McLeod

    We started playing around with this recipe for homemade smash burgers during the pandemic. A late night binge of Jon Favreau and chef Roy Choi’s show The Chef Show led to the purchase of a flat top and from there, an obsession was born. Five years later, it’s safe to say that this smash burger recipe is PERFECT. Tried and true! You may have seen us share this recipe over on Instagram, and today we’ve finally got it all laid out for you. The top to bottom, step-by-step to making crisp-edged, saucy (and yes, the sauce is KEY) burgers any time you want. 

    These burgers have become a vacation essential for our annual family visit to the San Juan Islands, and if we're lucky enough to have caught crab while we’re out there, we often add a bonus pile on top of the burger. More is more! Speaking of more, if you’ve got time, whip up some Homemade French Fries, and extra Burger Sauce to serve on the side. And if it’s a classic burger you crave, don’t miss our super classic Cheese Burger recipe. 

    ingredients laid out on the counter to make smash burgers and homemade burger sauce

    Ingredients

    Scroll down for the full recipe with measurements below.

    • Ground beef: Make it 80/20 so the burgers are nice and juicy, despite the smashing.
    • Sweet onion: Some of the onion will be cooked on the grill, and some will go directly into the burger sauce, so be sure you choose a sweet onion.
    • Yellow mustard: No fancy subs, please! Regular old yellow mustard is exactly the flavor your want on your smash burger. It’s aggressively tangy, and it stands up to the sweet ketchup and rich mayo.
    • Mayonnaise: The “secret” to any secret sauce is lots of mayo (ours included).
    • Ketchup: Regular Heinz ketchup is usually what we reach for, and it’s worth noting that ketchup flavor profiles can vary quite a lot brand to brand. It’s OK to try a different one, but sometimes we’ve been surprised by how assertively spiced some brands can be. A generic brand, or Heinz brand is probably the safest bet for this recipe, since we are going for really classic burger flavors.
    • Toppings: American cheese (nothing beats that almost-plastic-y American cheese melt factor), crisp Iceberg lettuce, and the juiciest tomato you can find. 
    chopped onion being cooked in olive oil in a cast iron skillet to be used on top of smash burgers
    a bowl of burger sauce made with mustard, mayonnaise, ketchup, and chopped onion

    How To Make The Best Smash Burgers

    1. Roll out the burger patties. We don’t mix anything into the beef, just grab about ¼ pound of ground beef per person, roll it into a ball and that’s it.
    2. Sauté some onion to use on top of the burgers and set them aside.
    3. Cut yourself some squares of parchment paper. P.S. All three of these first steps could be done a few hours ahead of time, if you’re cooking these up for a big group.
    4. Make the burger sauce by stirring together mustard, mayonnaise, ketchup, and onion.
    5. Place your ground beef balls on the hot flat top or skillet. Use the parchment paper to help you flatten the beef into ultra- thin patties. This is the smash part of the smash burgers! And yes, your kids will want to help. If they’re old enough, let ‘em!
    6. Flip the burgers.
    7. Top them with cheese. Once the cheese has melted…
    8. Tuck in! Be sure to serve up some classic sides with these, too. We love Potato Salad, Broccoli Salad, or even just a really crispy Classic Slaw. 
    Four raw ground beef balls, prepped and ready to be smashed into burgers
    a smash burger being smashed flat with parchment paper and a metal spatula in a cast iron skillet
    a smash burger cooking in a cast iron skillet topped with chopped cooked onions
    a smash burger cooking in a cast iron skillet topped with chopped cooked onions and melty american cheese

    Variations + Tips

    • Close-watchers may have noticed that we sometimes drizzle yellow mustard on the smash burger patties before we flip them! Yellow mustard adds a lot of salty tangy flavor to the patty, so mustard lovers should try this for sure.
    • Top the burgers with even more goodies! Crab meat (as we mentioned above) is admittedly pretty extra which is why it is delicious. But any additional burger topping you love would work well. We love the addition of sliced pickles, Sautéed Mushrooms, or even smashed avocado.
    • Make it vegetarian. You can definitely use a vegetarian ‘meat’ for the smash burger patty. Both Impossible and Beyond sell packages of ground “beef” that you can treat essentially how you’d treat real ground beef. Roll the patties, smash them, top them with the burger sauce and cheese, and you’ll barely know the difference!
    smash burger on a toasted bun, layered with crisp lettuce, cooked onion, melted American cheese, and a slice of fresh tomato
    smash burger on a toasted bun, layered with crisp lettuce, cooked onion, melted American cheese, and a slice of fresh tomato

    To Serve On The Side

    Find More Summer Inspiration

    For more recipe inspiration, follow us on Facebook, Instagram, TikTok and Pinterest or order our cookbook. We love when you share your meals. Tag us on Instagram using #themodernproper, and we’d love to hear what you think of this recipe in the comments below. Happy cooking!

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    Smash Burgers Recipe

    Published May 6, 2025

    By Natalie Mortimer

    • Serves:  4
    • Prep Time:  10 min
    • Cook Time:  5 min
    • Calories:  618
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    Description

    Homemade smash burgers are a summertime staple! Those crispy-edged burger patties with cheese and homemade burger sauce oozing down the sides are fast, easy and impossible not to love.

    Ingredients

    • 1 pound 80/20 ground beef
    • 2 tablespoons extra-virgin olive oil
    • 1 large sweet onion, chopped
    • ¼ cup yellow mustard
    • ¼ cup mayonnaise
    • ¼ cup ketchup
    • 2 teaspoons kosher salt
    • 4 slices American cheese
    • 4 sesame seed buns, halved
    • Shredded Iceberg lettuce
    • 1 large tomato, sliced

    Method

    1. Divide the ground beef into 4 equal pieces and roll into balls. 

      Four raw ground beef balls, prepped and ready to be smashed into burgers

    2. Heat the oil in a cast iron skillet or flat-top grill over high heat. Once the oil is glistening, add half of the onion and cook, stirring often, until browned, about 4 minutes. Transfer to a plate and return the skillet over high heat. 

      chopped onion being cooked in olive oil in a cast iron skillet to be used on top of smash burgers

    3. Meanwhile, in a small bowl, combine the mustard, mayonnaise, ketchup, and the remaining onion. 

      a bowl of burger sauce made with mustard, mayonnaise, ketchup, and chopped onion

    4. Once the oil is smoking, working one at a time, add a beef ball and top it with a small square of parchment paper. Using a thick spatula, press the beef into a ⅛-inch-thin patty. (The beef may break apart around the edges–that's ok!) Remove the parchment, season the patty with ¼ teaspoon of the salt, and cook until browned, about 2 minutes. Flip the patty, season it with ¼ teaspoon of the salt, and top it with 1 tablespoon of the cooked onion and a slice of cheese. Cook for about 1 minute more, or until the cheese has melted. Transfer the burger to the bottom half of a bun and repeat with the remaining ingredients.

      a smash burger cooking in a cast iron skillet topped with chopped cooked onions and melty american cheese

    5. Top each burger with the burger sauce, lettuce, tomato, and top half of a bun. Serve immediately.

      smash burger on a toasted bun, layered with crisp lettuce, cooked onion, melted American cheese, and a slice of fresh tomato

    Nutrition Info

    • Per Serving
    • Amount
    • Calories 618
    • Protein 29 g
    • Carbohydrates 33 g
    • Total Fat 47 g
    • Dietary Fiber 3 g
    • Cholesterol 26 mg
    • Sodium 1552 mg
    • Total Sugars 9 g

    Smash Burgers

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