Mustard-Fried Smash Burger with Secret Sauce Tips, FAQ & printable recipe

Tips for success

For an extra touch of flavor, toast your buns with a small amount of butter in the same pan used for the beef. This adds a subtle richness that complements the savory patties. Be careful not to burn them, as they toast very quickly over high heat. The goal is a light, golden brown finish that provides a crunch without overpowering the delicate texture of the sponge dough.

When smashing the patties, use a heavy, flat-bottomed object like a dedicated burger press or a thick spatula. Apply firm, even pressure for about 10 seconds to ensure the edges become thin and crispy.

Avoid lifting the spatula too quickly; let the heat do the work. If the meat sticks, give it another few seconds. The resulting crust is the defining feature of a great smash burger, so do not rush this critical step.

Variations

• Spicy Smash Burger: Add a tablespoon of chopped pickled jalapeños to the secret sauce for an extra kick of heat that cuts through the richness of the cheese.
• Bacon Smash Burger: Incorporate two strips of crispy, cooked bacon on top of each patty before adding the cheese for a smoky, salty flavor profile.

Storage and make-ahead

Fridge

Store in an airtight container for up to 3 days.

Reheat

Reheat in a skillet over medium heat until warmed through.

If you have leftovers, allow the patties to cool to room temperature for no more than two hours. Once cooled, store the patties and buns in separate airtight containers. This prevents the buns from becoming soggy due to the moisture from the meat and sauce. Consume within three days for the best quality and safety, ensuring they are kept in the coldest part of the refrigerator.

You can prepare the secret sauce up to 24 hours in advance and store it in the refrigerator. The flavors will actually improve as they meld over time. You can also dice the onions and keep them in a sealed container.

However, the beef patties should always be shaped and cooked fresh to ensure the best texture and safety. Toast the buns just before serving to maintain their integrity and warmth.

Serving ideas

Serve these burgers immediately while the patties are still piping hot and the crust is at its crispiest. A smash burger is a meal best enjoyed fresh off the griddle.

Pair them with simple sides like classic potato chips or a fresh green salad to balance the richness of the beef and cheese. The goal is to let the burger be the star of the plate, so keep the accompaniments minimal and light.

Provide extra napkins, as these burgers are intentionally juicy and flavorful. If you are serving a crowd, set up a station with the prepared sauce, pickles, and onions so guests can customize their own burgers if desired.

Ensure the cheese is melted to perfection and the buns are warm. Presentation is simple but effective: focus on the layers and the contrast between the crispy beef and the soft, toasted bun.

Frequently asked questions

Recipe card

Mustard-Fried Smash Burger with Secret Sauce

Prep 15 minCook 10 minTotal 25 minServes 2

Ingredients

• 1/3 cup mayonnaise
• 2 tbsp ketchup
• 2 tbsp sweet pickle relish
• 1 tsp white vinegar
• 1 yellow onion, diced
• 4 oz ground beef patties
• 2 tbsp yellow mustard
• 4 slices American cheese
• 2 sponge dough buns, toasted
• dill pickles, for serving

Instructions

1. In a small mixing bowl, whisk together the mayonnaise, ketchup, sweet pickle relish, and white vinegar until smooth and well combined. Set the sauce aside to allow the flavors to meld while preparing the rest of the ingredients.
2. Place the diced yellow onion in a skillet over medium heat. Sauté the onions until they are soft, translucent, and golden brown. Remove them from the heat and keep warm until assembly.
3. Heat a heavy steel pan or flat top griddle to 450°F (232°C). Place the ground beef patties onto the hot surface and smash them thin with a heavy spatula. Immediately squirt the yellow mustard onto the raw top side of the patties.
4. Once a dark, crispy crust has formed on the bottom, flip the patties over. Top each patty with a slice of American cheese and cook until the cheese is melted and the internal temperature reaches 160°F (71°C).
5. Toast the sponge dough buns until golden. Spread the prepared secret sauce on both sides of the bun. Place the cheeseburger patties on the bottom bun, top with caramelized onions and dill pickles, then finish with the top bun.

Contains: gluten, eggs, mustard, milk

Estimated nutrition per serving

Calories

580

Protein

28 g

Carbohydrates

22 g

Fat

42 g

Fiber

1 g

Sugar

5 g

Sodium

850 mg

Automatic estimate from the ingredient list, not laboratory-verified.