Steak + Truffle Burger Recipe

Form patties

Divide the 1.25 lb ground Guernsey beef into two equal portions (about 10 oz each). Gently form into loose patties about 3/4-inch thick and slightly larger than the buns. Do not overwork the meat. Season both sides with 1 tsp kosher salt and 1/2 tsp freshly ground black pepper just before cooking.

Cook patties

Heat a heavy skillet or cast-iron pan over medium-high heat until very hot. Add 1 tbsp neutral oil and swirl. Add patties and cook without moving for 3-4 minutes to develop a crust. Flip and cook 2-3 minutes for medium-rare (adjust time to desired doneness). In the last 60–90 seconds, place a slice of Mountainoak truffle gouda on each patty, cover the pan briefly to melt the cheese. Remove and tent loosely with foil to rest 3 minutes.

While patties rest (or simultaneously), make the duxelles. Heat 1 tbsp unsalted butter and 1 tsp olive oil in a skillet over medium heat. Add the finely minced shallot and cook 1–2 minutes until translucent. Add the chopped mushrooms and cook, stirring occasionally, until they release their moisture and it evaporates, about 6–8 minutes. Add the minced garlic and cook 30 seconds until fragrant. Deglaze with 2 tbsp dry white wine (if using) and continue cooking until liquid is absorbed. Stir in 1/2 tsp fresh thyme, 1/2 tsp salt, and 1/4 tsp black pepper. Continue cooking until the mixture is fairly dry and paste-like, about 2–3 more minutes. Remove from heat and keep warm.

Prepare the onion batter and oil. Combine 1/2 cup flour, 2 tsp cornstarch, 1/4 tsp smoked paprika, and 1/2 tsp kosher salt in a bowl. Add 1/2 cup very cold club soda and whisk just until a thin batter forms; it should cling lightly to the onions. Heat 2 cups neutral oil in a heavy pot or fryer to 350°F (175°C).

Coat and fry onions. Toss the very thinly sliced onion in the batter to coat. Working in batches, gently shake off excess batter and fry the onion strings until golden brown and crisp, about 1–2 minutes per batch. Use a slotted spoon to transfer to a paper-towel-lined tray and immediately season with a pinch of salt. Keep warm in a low oven (200°F/95°C) if making ahead.

Make the aioli. In a small bowl combine 1/2 cup mayonnaise, 2 mashed roasted garlic cloves, 1 tsp lemon juice, 1/2 tsp Dijon mustard, 1/4 tsp truffle oil (optional), 1/4 tsp salt, and 1/8 tsp freshly ground black pepper. Whisk until smooth and taste-adjust with more lemon or salt as needed. Chill until ready to assemble.

Prepare potatoes and par-cook. Place the cut fries in a bowl of cold water and soak 20–30 minutes to remove excess starch. Drain and pat completely dry. Heat neutral oil in a deep pot to 325°F (160°C). Fry the potatoes in batches for 3–4 minutes until tender but not browned. Remove and drain on paper towels.

Finish frying. Raise oil temperature to 375°F (190°C). Fry the par-cooked fries in batches until golden and crisp, 2–3 minutes. Drain on paper towels, season immediately with 1 tsp kosher salt and 1/4 tsp black pepper, and keep warm.

Toast buns. Halve the brioche buns and butter the cut sides with 1 tbsp unsalted butter. Toast in a skillet or under a broiler until golden and lightly crisp, about 1–2 minutes.

Assemble burgers. Spread a generous tablespoon of roasted garlic aioli on the bottom bun. Add butter lettuce leaf and a tomato slice. Place the truffle gouda-topped beef patty on top, then spoon about 2 tbsp wild mushroom duxelles over the cheese. Top with a handful of crispy onion strings and optional pickle slices. Spread a little aioli on the top bun and close.

Serve. Plate each burger with a portion of fresh cut fries. Offer extra aioli on the side for dipping.