Japanese Wagyu Smash Burger with Caramelized Onions & Wasabi Mayo

This Japanese Wagyu smash burger is a study in contrasts: a shatteringly crisp, lacy crust giving way to buttery, tender beef, all wrapped in a soft brioche bun with sweet caramelized onions and a wasabi mayo that delivers a clean, sinus-clearing kick.

The video shows the entire process in under a minute, but the technique is simple enough for any home cook to master. The result is a double-patty tower of indulgence that feels both familiar and exciting, perfect for a weekend dinner or a special treat.

The secret to this burger lies in the smash technique. Pressing the Wagyu balls onto a screaming-hot griddle maximizes surface area, creating an intense Maillard reaction that produces deep, beefy flavor and those coveted crispy edges.

The wasabi mayo, made with Japanese Kewpie mayonnaise, adds a creamy, tangy richness that cuts through the fat. Caramelized onions bring sweetness, and the melted cheese ties it all together. This recipe walks through each step, from forming the beef balls to assembling the final burger, so the result is as impressive as it is delicious.

Ingredients

Why this recipe works

Smashing the beef on a hot griddle creates an exceptionally thin patty with a large surface area, which means more contact with the pan and a deeper, more complex crust.

The Maillard reaction is responsible for the savory, roasted flavors that make this burger so satisfying. The high heat also renders the Wagyu fat quickly, basting the meat in its own juices and keeping the interior tender and moist.

The wasabi mayo is not just a condiment; it is a counterpoint. The creaminess of the Kewpie mayonnaise and the sharp, sinus-clearing heat of wasabi balance the richness of the beef and the sweetness of the onions. The soy sauce adds umami, and the furikake brings a subtle nuttiness and a hint of sesame. Together, they create a sauce that elevates the burger without overwhelming it.

Notes and substitutions

Wagyu beef is prized for its high fat content and buttery texture, but regular ground beef with an 80/20 ratio works well too. The key is to use meat that is well-marbled and freshly ground. If using Wagyu, handle it as little as possible to avoid melting the fat before it hits the pan. The beef balls should be loosely packed and well-chilled.

A heavy cast iron griddle or skillet is essential for the smash technique. It retains heat and provides a flat, even surface. A steel burger press is ideal, but a sturdy spatula can work if you press down firmly.

For the wasabi mayo, Japanese Kewpie mayonnaise is preferred for its richer flavor and creamier texture, but regular mayonnaise can be used with a dash of rice vinegar and sugar to mimic the tang.

• Wagyu beef: Regular ground beef (80/20) for a more affordable option; the flavor will be less rich but still delicious.
• Kewpie mayonnaise: Regular mayonnaise mixed with a pinch of sugar and rice vinegar to mimic the tangy sweetness.
• Brioche buns: Potato rolls or soft hamburger buns work well and are easier to find.
• American cheese: Sharp cheddar or provolone for a different melt and flavor profile.

Equipment

• Cast iron griddle or heavy skillet
• Heavy steel burger press or spatula
• Mixing bowl
• Whisk
• Ramekin or small bowl
• Spatula
• Cutting board
• Knife