Our Smash Burger Sauce, aka smash sauce, is as simple as can be and absolutely perfect. A harmony of two types of mustard and mayonnaise is all you need to turn a crispy, craggy-edges smash burger into a masterpiece. 

Why This Recipe Works

A smash burger with all the fixings? How could anyone resist. One of those essential toppings is some kind of burger sauce or condiment. We aren’t here to hate of mustard or ketchup, but for the ultimate smash burger we wanted to come up with a sauce that no other could rival.

What we came up with is stupidly simple, but also so much tastier than more smash sauces made with a laundry list of ingredients. Our smash sauce—made with just 3 ingredients—is tangy, savory and perfectly decadent. 

balls of ground beef, burger buns, lettuce, pickles, cheese, mustard and mayo, and sliced onions arranged on a baking sheet

Ingredient Notes 

Prepared Yellow Mustard

We love a load of yellow mustard on just about everything. And smash burgers are now exception. Prepared yellow mustard, with its potent tang, is ideal for cutting through the fatty meat and dose of mayonnaise in the sauce. 

Whole Grain Mustard

For some mild horseradish-esque tang, we add a dollop of whole grain mustard (also called whole-grain Dijon). We like Boetje’s or Maille


The addition of some mayonnaise to this sauce is absolutely stellar. It mellows out the boldness of the mustard while also adding a bit of decadence. We like to use olive oil mayonnaise, but as we always say, the best mayonnaise is the one you like best 

test kitchen Tips

  • Many recipes for smash burgers will have you spread the sauce on just the bottom bun—it’s so good that we prefer to put it on both the top and bottom bun.
  • To ensure the buns don’t get soggy before placing the thin patty on top, we recommend toasting the buns. Just a minute on a hot griddle or cast-iron skillet is all a brioche hamburger bun needs to become perfectly toasted.
smash burger on a wooden cutting board with pickles set in the background

Variations on Smash Sauce

  • Add a splash of Worcestershire for an added note of savoriness. 
  • If you love a horseradish kick, add a heaping teaspoon of prepared horseradish to the sauce.
  • We love a little minced onion on our burgers. If you do too, add some to the sauce. 
  • In keeping with traditional smash burger sauces, add some minced pickles and pickle juice to the sauce.
  • Add a little spice by dropping in a few dashes of hot sauce. We recommend Tabasco or Frank’s.
  • For a dose of tomato flavor, add a squeeze of Ketchup. We love Organicville or Hunts
  • Try adding some minced fresh garlic or garlic powder for an add flavor boost. 


What’s in a traditional smash burger smash sauce? 

Traditionally, smash burger smash sauce is made with mayonnaise, mustard, pickle juice and minced pickles. Since we already load up our smash burgers with sliced pickles, onion slices, iceberg lettuce, and American cheese, we found the addition of pickles in the sauce unnecessary—the burger is already flavorful enough.

How long does this smash burger sauce last?

Since it’s only made with long-lasting condiments, this sauce will last for a couple of weeks in the refrigerator. Just be sure to store it in an airtight container. 

How else can I use this secret sauce?

We love to use this smash burger sauce on all kinds of burgers (try our Salmon Burger Recipe or Shrimp Burger Recipe) sandwiches including classic deli-style sandwiches, grilled cheese and even brats or hotdogs. We also love to serve it as a fry sauce with French fries or our crispy Polenta Fries

Do I need to season the sauce with salt and pepper?

We find the mustard to be salty enough so you can skip adding any salt. As for black pepper, add it to taste if you prefer! 

Smash Burger Sauce

4.67 from 3 votes
Prep Time 5 minutes
Total Time 5 minutes
Yield 4 servings (¾ cup)
Category Sauce/Condiment
Cuisine American


Our go-to smash burger is as simple and as delicious as can be. Made with equal parts yellow mustard, whole grain mustard, and mayonnaise. Sound too simple? Give it a try and you’ll see why we’re obsessed.



  • In a small bowl, whisk together mustards and mayo. Use as desired on Smash Burgers.


Store smash sauce in an airtight glass container in the refrigerator for up to 2 weeks.


Serving: 3tablespoonsCalories: 70kcalCarbohydrates: 2.5gProtein: 1gFat: 4.5gCholesterol: 5mgSodium: 632mgFiber: 0.5gSugar: 1g
Like this? Leave a comment below!I love hearing from you and I want to hear how it went with this recipe! Leave a comment and rating below, then share on social media @zestfulkitchen and #zestfulkitchen!
two burger bun halves set on a wood cutting board. One half topped with sauce, the other half topped with a burger

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About The Author

Lauren Grant is a professional culinary food scientist, food writer, recipe developer, and food photographer. Lauren is a previous magazine editor and test kitchen developer and has had work published in major national publications including Diabetic Living Magazine, Midwest Living Magazine, Cuisine at Home Magazine, EatingWell.com, AmericasTestKitchen.com, and more.

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