Active Time:

45 mins

Total Time:

1 hr 30 mins

Yield:

4 servings

Two juicy beef patties are sandwiched with buttery melted onions and a creamy special sauce in these smash burgers. Chef Johnny Spero of Bar Spero in Washington, D.C., affectionately refers to the seasoning as “dad salt,” a combination of kosher salt, black pepper, and MSG. The special sauce is smoky, nicely balanced with the salt and sherry, and has bits of zippy, crunchy cornichons throughout. For extra richness, puree a soft-boiled egg into the sauce to add depth and oomph.

While the team at Bar Spero grinds their own burger blend, they recommend sourcing a high-quality combination of ground chuck and brisket from your local butcher shop.

Frequently asked questions

What is MSG?

MSG, or monosodium glutamate, is a crystallized food additive made from glutamic acid. It doesn’t have a strong taste on its own, but combined with other ingredients, it amps up other savory flavors.

How do I make the soft-boiled egg?

For a soft-boiled egg, bring a small pot of water to a boil over medium-high. Add 1 egg, and boil for 7 minutes. Transfer to a bowl of ice water to cool completely before peeling.

Notes from the Food & Wine Test Kitchen

Use leftover burger salt on roasted vegetables or grilled chicken. Leftover special sauce and soubise onions are great on hot dogs, chicken sandwiches, or breakfast sandwiches.

Make ahead

The burger salt can be stored in an airtight container at room temperature for up to 2 weeks. Additionally, the special sauce and soubise onions can be stored in airtight containers in the refrigerator for up to 2 days.

Suggested pairing

These rich, beefy burgers require a powerful wine like a full-bodied Cabernet Sauvignon. We like Daou Paso Robles.

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Ingredients

Burger Salt

1 tablespoon black pepper
1 tablespoon kosher salt
3/4 teaspoon MSG (such as Ajinomoto)

Special Sauce

1 cup mayonnaise
1 garlic clove, grated
1 teaspoon sherry vinegar
3/4 teaspoon smoked paprika
1/2 teaspoon yellow mustard
1/4 teaspoon kosher salt
1/4 teaspoon MSG (such as Ajinomoto)
1 soft-boiled egg (optional)
2 tablespoons finely chopped cornichons

Soubise Onions

1 yellow onion, thinly sliced (about 2 1/2 cups)
2 teaspoons granulated sugar
2 teaspoons kosher salt
1/2 cup unsalted butter (4 ounces), cut into 1-inch cubes

Smash Burgers

2 pounds burger blend ground beef (such as ground chuck and brisket)
Cooking spray
8 slices American cheese
4 sesame seed hamburger buns, split and toasted
1/2 cup sliced half-sour pickles (such as Ba-Tampte)

Directions

Make the burger salt

Stir together black pepper, kosher salt, and MSG in a small bowl; set aside.
Make the special sauce

Combine mayonnaise, garlic, vinegar, paprika, mustard, kosher salt, MSG, and egg, if using, in a blender. Process until smooth, about 1 minute. Transfer mixture to a medium bowl; stir in cornichons. Cover and refrigerate until ready to use.
Make the soubise onions

Toss together onions, sugar, and salt in a medium saucepan to coat. Let stand at room temperature 30 minutes. Add butter, and cook over medium, stirring occasionally, until onions are softened and translucent but not browned, 25 to 30 minutes. Remove from heat, and set aside.
Make the smash burgers

Shape meat into 8 (4-ounce) balls (about 1/2 cup each). Heat a large cast-iron skillet or griddle over medium-high. Working in batches, place meat balls in skillet, spacing at least 3 inches apart. Lightly coat the back of a heavy metal spatula with cooking spray, and smash each ball to flatten to about 1/3-inch thickness. (Alternatively, place a small sheet of parchment paper on each meat ball, and smash using a cast-iron burger press; remove parchment.) Sprinkle top of each flattened patty with 1/4 teaspoon reserved burger salt. Cook until bottoms are browned and lightly crisp, about 2 minutes. Flip patties, and sprinkle each with 1/4 teaspoon burger salt. Reserve remaining burger salt for another use (see Note). Top each patty with 1 cheese slice. Cook until cheese is melted and patties are cooked through, about 2 minutes.
Place 2 tablespoons reserved soubise onions on each bottom bun. Top each with 2 patties, 1 1/2 tablespoons special sauce, and 4 to 5 pickle slices. Cover with top buns. Reserve remaining soubise onions and special sauce for another use (see Note). Serve immediately.