Blue Horsey Melt Recipe

Place the thinly sliced red onion in a small bowl. Add white wine vinegar, water, sugar and 1/4 tsp kosher salt. Stir to combine, pressing onions down so they are submerged. Let sit at room temperature for at least 20 minutes (or up to 2 hours). Drain before using. Reserve about a tablespoon of the pickling liquid if you want extra brightness in the sandwich.

In a small bowl, whisk together creamed horseradish, mayonnaise, Dijon mustard, lemon juice, and heavy cream or milk (if using) until smooth. Season with 1/8 tsp salt and 1/8 tsp freshly ground black pepper. Taste and adjust: add more horseradish for heat or more mayo to mellow. Refrigerate until ready to assemble.

Prepare the mushrooms and peppers

Heat 1 tablespoon olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Add the sliced mushrooms in a single layer; let them brown without overcrowding, stirring occasionally, about 5–7 minutes, until browned and any liquid has evaporated. Season with 1/4 tsp kosher salt and 1/4 tsp black pepper. Add the roasted red pepper strips and cook 1–2 minutes more to warm through. Transfer the mixture to a bowl and keep warm.

Cook the shaved steak

Return the skillet to medium-high heat and add the remaining 1 tablespoon butter. When hot, add the shaved steak in an even layer (work in batches if needed). Season steaks lightly with remaining 3/4 tsp kosher salt and 3/4 tsp black pepper distributed across batches. Sear 1–2 minutes, then stir and continue cooking just until no longer pink, about 2–3 minutes total (thin slices cook quickly). Remove from heat and combine with the cooked mushrooms and peppers. Toss in drained marinated onions (reserve a little for garnish if desired). Keep warm.

Toast the hoagie rolls

Preheat broiler or oven to high broil. Lightly brush the cut faces of the hoagie rolls with about 1 tsp olive oil or spread a thin layer of butter. Place rolls cut-side up on a baking sheet and broil 1–2 minutes until lightly golden and crisp. Watch carefully to avoid burning.

Assemble and melt

Spread a generous tablespoon of the horsey sauce on the cut face of each bottom roll and a thin layer on each top roll (reserve extra for serving). Pile the steak, mushroom, pepper and marinated onion mixture evenly onto the bottom halves. Sprinkle the crumbled Gorgonzola cheese over the hot filling (about 2 oz per sandwich). Place assembled halves under the broiler just long enough to soften and slightly melt the Gorgonzola, about 1–2 minutes. Remove when cheese is just melted and filling is hot.

Finish: Remove from oven, add any reserved marinated onions and a sprinkle of chopped parsley if using. Close sandwiches, cut in half if desired, and serve immediately with extra horsey sauce on the side.