Wagyu Smash Patty Burger Recipe

In a small bowl, combine 1/2 cup mayonnaise, minced garlic, 1 tsp crushed black peppercorns, 1 tsp lemon juice, 1/2 tsp Dijon mustard and 1/4 tsp kosher salt. Whisk until smooth and taste; adjust salt or lemon as needed. Cover and refrigerate while you prepare the rest (can be made up to 24 hours ahead).

Heat a 10-inch skillet over medium-low heat. Add 1 tablespoon butter or neutral oil. Add thinly sliced red onion and 1/4 tsp kosher salt. Cook slowly, stirring every 2–3 minutes, until onions are deep golden and tender, about 20–30 minutes. If onions are sticking or not browning, add a splash of water. In the last 5 minutes, stir in 1/2 teaspoon brown sugar (optional) to deepen color and flavor. Remove from heat and set aside.

Peel (optional) and wash the 2 russet potatoes. Using a mandoline or very sharp knife, cut potatoes into very thin shoestring fries (about 1/8 inch / 3 mm). Immediately place cut fries in cold water and soak 10–20 minutes to remove surface starch; then drain and pat completely dry with clean kitchen towels or paper towels.

In a heavy-bottomed pot or deep fryer, heat 1 cup beef tallow (supplement with neutral oil if needed to reach 2–3 inches depth) to 325°F (160°C). Fry the potatoes in small batches for 3–4 minutes until just tender and pale gold. Remove with a slotted spoon to a paper towel-lined tray and let rest 3–5 minutes.

Increase the oil temperature to 375°F (190°C). Return the fries in batches and fry until crisp and deep golden, about 1–2 minutes. Drain on paper towels and immediately season with 1 tsp kosher salt. Keep warm in a low oven (200°F / 95°C) on a tray while finishing burgers.

Divide 1 lb Akaushi ground beef into four equal portions (about 4 oz each). Lightly roll into loose balls; do not pack tightly — loose balls give better smash texture. Season one side of each ball with a light pinch of kosher salt and a light grind of black pepper.

Preheat a heavy cast-iron griddle or skillet over high heat until very hot. Add 1 tablespoon neutral oil and spread. Working one or two patties at a time, place a beef ball seasoning-side down on the hot surface. Immediately press firmly with a heavy spatula or a burger press lined with parchment to flatten into a very thin patty (about 1/4 inch thick). Hold pressure for 10–15 seconds to set the crust.

Cook smashed patties without moving for 2–2.5 minutes until deeply browned and edges are crisp. Season the just-cooked top with a small pinch of salt. Flip, immediately place a slice of Muenster cheese on each patty, and cook an additional 30–45 seconds until cheese melts and patty is cooked through (medium-well in thin smash style). Remove and keep warm on a tray.

Split brioche buns and butter cut sides with 1 tablespoon unsalted butter total. Toast buttered cut sides on the griddle until golden, about 30–60 seconds. Place 1–2 washed lettuce leaves and 2 thin tomato slices on each bottom bun. Season tomato lightly with a pinch of salt.

Spread about 1 tablespoon black peppercorn aioli on the cut side of each top bun (adjust to taste). On each bottom bun (already dressed with L & T), place two smashed Muenster-topped Akaushi patties stacked (for a double: use two patties per burger). Spoon a generous portion of caramelized onions on top of the patties. Add cracked black pepper to taste.

Place the aioli-smeared top bun on the stacked patties and slightly press to compact. Serve immediately with a side of warm beef tallow shoestring fries.