Truffle Steak Melt Recipe

Marinate steak

Combine 1 tbs olive oil, 1 tsp soy sauce, 1 tsp Worcestershire sauce, 1 minced garlic clove, 1 tsp black pepper and 1/2 tsp kosher salt in a shallow dish. Add the steak and coat both sides. Let sit at room temperature 20–30 minutes (or refrigerate up to 2 hours; bring back to room temp before cooking).

Cook steak

Heat a cast-iron skillet or heavy pan over medium-high heat until shimmering (about 3–5 minutes). Add a light film of oil. Sear the steak 3–4 minutes per side for medium-rare (internal 125–130°F / 52–54°C), adjusting time for thickness and desired doneness. During the last minute, baste with any rendered juices. Transfer steak to a cutting board and tent loosely with foil; rest 5–10 minutes before slicing thinly against the grain into 1/4-inch strips.

Caramelize onions

While steak rests, heat 1 tbs butter + 1 tsp olive oil in a medium skillet over medium-low. Add the thinly sliced onion and 1 tsp brown sugar, sprinkle with 1/4 tsp salt. Cook slowly, stirring occasionally, 20–25 minutes until soft, deeply golden and sweet. If onions stick, add 1–2 tbs water to deglaze and continue. Remove to a bowl when done.

Sauté mushrooms

In the same skillet, increase heat to medium. Add a small pat of butter and the sliced mushrooms. Cook without crowding, stirring occasionally, until browned, about 6–8 minutes. Season with 1/4 tsp salt, 1/4 tsp black pepper and 1 tsp fresh thyme. If using, deglaze the pan with 2 tbs red wine, scraping up browned bits, and cook until liquid mostly evaporates. Combine mushrooms with caramelized onions and keep warm.

Make truffle aioli

In a small bowl whisk together 1/2 cup mayonnaise, 1/2 tsp truffle oil, 1/2 tsp lemon juice, 1/2 tsp Dijon mustard, 1/4 tsp grated garlic, 1/8 tsp salt and 1/8 tsp black pepper. Taste and adjust: add a drop more truffle oil if you want stronger aroma (use sparingly). Chill until ready to assemble.

Prepare bread

Butter one side of each of the 4 sourdough slices lightly (about 1/2 tsp per slice). Heat a clean skillet over medium. Toast buttered sides down until golden, 1–2 minutes. Flip and toast the other side very briefly so both sides are warm and slightly crisp. Remove and keep warm.

Assemble sandwiches

Spread a generous tablespoon of truffle aioli on the untoasted side of two bread slices (the sides that were not buttered for grilling). Layer on 3 oz Havarti (divide evenly), then a helping of sliced steak (about half the sliced steak per sandwich), followed by a generous portion of caramelized onions and mushrooms. Top with remaining Havarti, a small handful of microgreens or arugula if using, and pickles/jalapeño slices if desired. Close with the top bread slices (buttered side out).

Grill to melt cheese

Return assembled sandwiches to the skillet over low-medium heat. Press gently with a spatula or a weighted press and cook 2–3 minutes per side, flipping carefully, until bread is crisp and Havarti is melted (cover pan with lid for 1–2 minutes to encourage melting if needed).

Finish and serve

Transfer sandwiches to a cutting board, let rest 1 minute, then slice in half on the bias. Serve immediately with any extra truffle aioli on the side for dipping.