Make RPM Steak’s Wagyu Smash Burger at Home

Smash burgers were already doing just fine before the pandemic — note the pre-2020 growth of chains like Shake Shack (est. 2001) or Smashburger (2007). But these ultra-thin burgers positively skyrocketed in omnipresence during lockdown, when, according to the Chicago Tribune, chefs often found themselves relying on simpler fare to feed the masses — and this staple of pressed chuck restaurants and diners is nothing if not nostalgia to the nth degree.

The smashed school of burger thought certainly has its naysayers, including those who believe that pressing down on your burger expels its juices and makes it dry. Indeed, while you’d be hard-pressed to find a red, rare center to a smash burger, that’s so not the point. Pressing down on the patty is the ideal way to dial up the char: with more surface area, a smash burger is positively begging for the high heat of a flat top — or, at home, a seasoned cast iron skillet set over high heat (crack a window and disable the fire alarm!) — to render it crisp and deeply browned.

Eddie Ishaq, executive chef of RPM Steak in Chicago, says a smash burger is “a vehicle for restaurants to put their unique stamp on an American classic.” His version, he says, marries luxury and accessibility in equal measure.

He begins with ground wagyu, which boasts a higher fat content than most ground beef due to the way these high-end Japanese cattle are raised. This choice, the chef says, adds “richness and depth of flavor” to the final burger, which is expertly counterbalanced not only by pickles — five per sandwich — but also a house-made sauce combining creamy kewpie mayonnaise with yuzu kosho, a Japanese condiment that Ishaq relies on quite frequently at RPM. The paste of fermented fresh chiles and with yuzu zest has been rising in the on-trend condiment ranks of late; for Ishaq, “it adds freshness and a hint of heat without being overpowering.”

Paired with a rich brioche bun and aged cheddar cheese, it’s a wow-worthy burger you can make at any time of year — grilling season be damned.

Wagyu Smash Burger (serves 2)

For the yuzu kosho sauce:

1 cup kewpie mayonnaise
1½ teaspoons fresh lime juice
4½ teaspoons granulated sugar
1½ teaspoons low-sodium soy sauce
2 tablespoons yuzu kosho
¼ teaspoon kosher salt

Combine all of the ingredients in a bowl and season to taste. Store any excess sauce in the fridge for up to seven days.

For the burger

2 4-inch brioche buns
1 pound ground wagyu beef, divided into 4 4-ounce pucks
4 slices aged cheddar
2 ounces (about 4 tablespoons) yuzu kosho sauce
10 pickle slices
Salt and pepper, to taste

Preheat the oven to 350 ºF. Season both sides of the burger patties with salt and pepper. Place the burgers in a hot cast iron skillet, and smash until about ¼ inch thick. Once a heavy crust has formed on one side, flip and press again.

Top two patties with a slice of cheddar, and allow the cheese to melt. Meanwhile, warm the buns in the oven.

Remove the buns from the oven, and dress both sides with yuzu kosho sauce. On the bottom half of each bun, arrange five pickle slices.

Stack the burger patties on the buns, then add the top bun. Serve.