Prime Rib Mushroom Melt Recipe

Prepare mushrooms

Wipe mushrooms clean with a damp cloth and slice about 1/4-inch thick. Mince shallot and garlic, measure thyme leaves.

Heat a large skillet over medium-high heat. Add 1 tablespoon olive oil and 1 tablespoon butter. When butter foams, add sliced mushrooms in an even layer (work in batches if necessary so they brown rather than steam).

Cook, undisturbed for 3–4 minutes, then stir and continue to cook 2–3 minutes until golden and any liquid has evaporated. Add minced shallot and cook 1 minute until softened.

Add garlic and thyme, cook 30–45 seconds until fragrant. Season with 3 pinches kosher salt and 1 tsp freshly ground black pepper. Remove from heat and set aside.

In a small bowl, whisk together 3 tbsp prepared horseradish, 4 tbsp mayonnaise, 2 tbsp sour cream, 1 tsp lemon juice and 1 tsp Dijon mustard until smooth.

Season with a pinch of kosher salt and black pepper, taste and adjust horseradish or lemon to preference. Refrigerate until ready to serve.

Pour 2 cups beef au jus or low-sodium beef broth into a small saucepan and warm over medium heat.

Stir in 2 tbsp beef drippings (if using), 1 tsp Worcestershire sauce and 1 tsp soy sauce. Bring just to a gentle simmer, taste and add a pinch of freshly ground black pepper. Keep warm on the lowest burner setting or transfer to a small serving vessel.

Warm the sliced smoked prime rib: place the 1 lb of thinly sliced prime rib in a wide skillet set over medium heat with 1 tablespoon butter. Gently toss or fold the slices for 1–2 minutes just until warmed through (avoid overcooking to preserve pinkness). Remove and tent lightly with foil to keep warm.

Split brioche buns and lightly butter cut sides with remaining 1 tablespoon butter. Toast buttered sides in a hot skillet or on a griddle over medium heat until golden, 1–2 minutes.

To assemble each sandwich: spread about 1 tbsp creamy horseradish on the bottom bun. Pile 4 oz (approximately 1/4 lb) warmed prime rib slices onto the bun (divide the 1 lb evenly across 4 sandwiches). Top the meat with a generous portion of sauteed mushrooms (about 3 tbsp per sandwich).

Top the mushrooms and meat with one provolone slice. If you prefer the cheese melted, place assembled open-faced sandwiches under a broiler for 45–60 seconds or cover the skillet with a lid for 30–45 seconds until the cheese softens and barely melts.

Close the sandwich with the top brioche bun, garnish with a sprinkle of chopped parsley if desired. Serve immediately with a small ramekin of warm au jus and extra creamy horseradish on the side for dipping.