Truffle Mushroom Burger Recipe

Prepare mushrooms

Finely chop mushrooms (or pulse in a food processor in short bursts until finely minced). Pat any excess moisture off with paper towels.

Heat 1 tablespoon butter and 1 teaspoon olive oil in a skillet over medium heat. Add minced shallot and sauté 1–2 minutes until translucent.

Add chopped mushrooms and cook over medium-high heat, stirring frequently, until the moisture evaporates and the mushrooms begin to brown, about 8–10 minutes.

Add minced garlic and thyme and cook 1 minute more. Deglaze the pan with 2 tablespoons white wine, scraping up browned bits. Continue cooking until wine evaporates.

If using, stir in 1 teaspoon heavy cream for a silkier texture. Remove from heat, stir in 1/2 teaspoon truffle oil, season with 1/2 teaspoon salt and 1/4 teaspoon black pepper. Let cool slightly; set aside.

Heat 1 tablespoon butter and 1 teaspoon olive oil in a sauté pan over medium-low heat. Add thinly sliced onion and a pinch (1/4 tsp) salt.

Cook slowly, stirring every few minutes, until onions soften and turn golden brown, about 20–25 minutes. If they stick, reduce heat and add a splash of water to deglaze.

Optional: Stir in 1/2 teaspoon brown sugar about halfway through to encourage browning, and finish with 1 teaspoon balsamic vinegar for brightness. Remove from heat and keep warm.

Preheat oven to 400°F (200°C). Slice top off garlic head to expose cloves, drizzle with 1/2 teaspoon olive oil, wrap in foil and roast 30–35 minutes until soft and golden. Cool slightly.

Squeeze roasted garlic cloves into a bowl and mash into a paste. Mix with 1/2 cup mayonnaise, 1 teaspoon lemon juice, 1/4 teaspoon salt and 1/8 teaspoon black pepper until smooth. Taste and adjust seasoning. Refrigerate until assembly.

Heat about 1 cup vegetable oil in a small saucepan or skillet to 350°F (175°C) or until a small piece of bread sizzles gently.

Whisk together 1/4 cup flour, 1 teaspoon cornstarch, and a pinch of salt. Add 1/2 cup cold sparkling water and whisk briefly to make a thin batter; it should cling lightly to onion rings.

Toss red onion rings in batter, shake off excess, and fry in batches until golden and crisp, about 1–2 minutes per batch. Drain on paper towels and season with 1/4 teaspoon salt while hot.

Divide 1 lb ground beef into 2 equal portions. Form each into a loose patty slightly larger than the bun (about 3/4-inch thick). Avoid overworking the meat. Season both sides with 1/2 teaspoon salt and 1/4 teaspoon black pepper per patty (total in ingredients accounts).

Heat a cast-iron skillet or griddle over medium-high heat. Add 1 tablespoon butter and let it melt and foam. Add patties and cook undisturbed 3–4 minutes until a browned crust forms.

Flip patties and immediately top each patty with a slice of Gruyère. Cook another 3–4 minutes for medium, or to desired doneness. If desired, cover skillet for 30–60 seconds to help cheese melt.

While patties rest for a couple minutes, butter the cut sides of brioche buns and toast in a separate pan or on the griddle until golden, about 1 minute.

Spread about 1 tablespoon roasted garlic aioli on the bottom half of each toasted brioche bun.

Place the cheese-topped beef patty on the aioli. Spoon about 2–3 tablespoons truffled mushroom duxelles over the patty.

Add 2–3 tablespoons caramelized onions on top of the duxelles, then a small handful (about 1/2 cup) of arugula.

Top with a small handful of crispy red onions (about 1–2 tablespoons) for crunch. If desired, drizzle a tiny amount (1/8–1/4 tsp) of extra truffle oil over the mushrooms for aroma.

Close with the top bun and serve immediately. Repeat for second burger.