Japanese Wagyu Smash Burger with Caramelized Onions & Wasabi Mayo Step-by-step instructions

Before you start

Before starting, gather all ingredients and equipment. Make the wasabi mayo by whisking together the Kewpie mayonnaise, wasabi paste, soy sauce, and furikake in a small bowl. Set aside.

Form the ground Wagyu beef into two equal balls and season generously with salt and pepper. Have the cheese slices, caramelized onions, and brioche buns ready. Preheat a cast iron griddle or heavy skillet over high heat for at least 5 minutes, until it is smoking hot.

Instructions

Prep the Sauce and Beef

1. 1Make the Wasabi Mayo
   In a small ramekin, combine the Japanese Kewpie mayonnaise, wasabi paste, soy sauce, and furikake seasoning. Whisk until smooth and pale green. Set aside.
   Look for The mayo turns a uniform pale green and is completely smooth.
   Tip Taste and adjust the wasabi to your preferred heat level, but keep it balanced.
2. 2Form the Beef Balls
   Divide the ground Wagyu beef into two equal portions and gently roll each into a ball. Do not overwork the meat; handle as little as possible to keep it tender. Season the outside of each ball with kosher salt and freshly ground black pepper.
   Look for The balls are loosely packed and hold their shape without cracking.
   Tip Chill the balls for 10 minutes before cooking if time allows; cold meat smashes better.

The wasabi mayo is smooth and pale green, with a balanced heat and umami. The beef balls are loosely packed and seasoned. The griddle is heating up, and the kitchen is filled with the anticipation of what is to come.

Smash and Sear

3. 3Heat the Griddle
   Place a cast iron griddle or heavy skillet over high heat and let it get screaming hot. This is essential for a proper crust.
   Look for A drop of water dances and evaporates immediately when the pan is ready.
   Tip Do not add oil; the Wagyu has enough fat to render and crisp the edges.
4. 4Smash the Patties
   Place the seasoned beef balls on the hot griddle, spaced apart. Immediately press each ball down with a heavy steel press or a sturdy spatula, flattening into thin patties about 4 inches wide. Press firmly for 10 seconds to maximize contact with the pan.
   Look for The patties are thin, with ragged edges that will crisp up.
   Tip Use a piece of parchment between the press and the meat to prevent sticking.
5. 5Sear the First Side
   Let the patties sear undisturbed for 2 minutes. Do not move or peek; the crust needs time to form. You will see the edges turn lacy and brown.
   Look for The edges are deeply browned and crispy, and the top still looks pink.
   Tip Resist the urge to press down again; that would squeeze out the juices.
6. 6Flip and Add Cheese
   Using a thin spatula, carefully flip each patty. Immediately drape one slice of American cheese over each patty so it melts as the second side cooks.
   Look for The cheese starts to melt and bubble around the edges.
   Safe temperature 160°F (71°C) internal temperature (ground meat)
   Tip If the cheese does not melt quickly, cover the pan with a lid for 30 seconds.
7. 7Cook the Second Side
   Cook for another 1 to 2 minutes, until the cheese is fully melted and the patties reach an internal temperature of 160°F (71°C) for ground beef. The second side will not get as crisp as the first, but it should be cooked through.
   Look for The cheese is fully melted and the patties feel firm to the touch.
   Safe temperature 160°F (71°C) internal temperature (ground meat)
   Tip If you have a thermometer, check the thickest part of the patty.

The patties are thin, with ragged edges that are browning and crisping. The smell of searing beef fills the air. After flipping, the cheese melts over the patties, and the stack builds. The internal temperature is on its way to 160°F (71°C).

Assemble and Serve

8. 8Stack the Patties
   Place one patty on top of the other. Spoon the caramelized onions over the top patty, letting them settle into the melted cheese.
   Look for The onions sit in the cheese and the stack holds together.
   Tip Keep the stack on the griddle for a moment so the onions warm through.
9. 9Toast the Buns
   While the patties finish, place the split brioche buns cut-side down on the hot griddle for 30 to 60 seconds, until golden and toasted.
   Look for The cut sides are golden brown with light grill marks.
   Tip Toasting in the beef fat adds extra flavor.
10. 10Assemble the Burger
    Slather the bottom bun with a generous amount of wasabi mayo. Place the double patty stack on top. Add the top bun and press down gently, letting the juices and melted cheese drip over the edges.
    Look for The burger is tall, with cheese and onions peeking out, and mayo spreading.
    Tip Serve immediately while the cheese is molten and the edges are crisp.

The buns are toasted, the wasabi mayo is spread, and the double patty stack is placed on the bottom bun. The top bun goes on, and the burger is pressed gently, causing juices and cheese to drip. The burger is tall, glossy, and irresistible.

Common mistakes

The most common mistake is not getting the pan hot enough. If the pan is not screaming hot, the patties will steam rather than sear, and you will not get the crispy crust.

Another mistake is pressing down on the patties after the initial smash, which squeezes out the juices and makes the burgers dry.

Also, avoid overworking the meat when forming the balls; handle it gently to keep the texture tender. Finally, do not add oil to the pan; the Wagyu has plenty of fat.

How to tell it’s done

The burgers are done when the internal temperature of the patties reaches 160°F (71°C) for ground beef. The first side should have a deep, dark brown crust with crispy, lacy edges.

The cheese should be fully melted and bubbly. The buns should be toasted to a golden brown. The assembled burger should be juicy, with the cheese and onions melding together, and the wasabi mayo adding a creamy, spicy finish.

• Ground meat: 160°F (71°C) in the thickest part
• Steaks, chops and roasts: 145°F (63°C) in the thickest part, then a 3-minute rest