Steak Sandwich Recipe

Bring beef to room temperature

Remove the beef tenderloin from the refrigerator 30 minutes before cooking so it comes close to room temperature for even cooking.

Pat the beef dry with paper towels. Season all sides evenly with 1 tsp kosher salt and 1/2 tsp freshly ground black pepper.

Preheat a heavy skillet or cast-iron pan over medium-high heat. Add 1 tbsp olive oil and heat until shimmering.

Sear the beef: place the tenderloin in the hot pan and sear 2–3 minutes per side until a deep brown crust forms. If using a whole tenderloin roast, sear all sides (including ends).

Transfer the seared beef to a 375°F (190°C) oven and roast until internal temperature reaches 125°F (51°C) for medium-rare — about 10–15 minutes for a 1 lb portion. Use a thermometer for accuracy. Remove from oven and tent with foil; rest 10 minutes (carryover will rise a few degrees).

While beef rests, split sandwich rolls and spread softened butter on cut sides. Toast cut sides in a dry skillet over medium heat until golden, about 1–2 minutes per side, then set aside.

After resting, thinly slice the beef against the grain into 1/4-inch slices. Keep warm.

Assemble each sandwich: spread a generous layer (about 1–2 tbsp) of horseradish cream on the bottom half of each roll, top with a portion of sliced beef, a spoonful of sautéed onions, and drizzle or dip with au jus as desired. Close sandwich and serve immediately.

Thinly slice 1 large yellow onion.

Heat 1 tbsp unsalted butter with 1 tsp olive oil in a medium skillet over medium heat until butter melts and foam subsides.

Add sliced onions, 1/2 tsp salt, 1/4 tsp black pepper, and a pinch (1/8 tsp) of sugar if using. Stir to coat.

Cook, stirring occasionally, until onions are soft and golden brown, about 12–18 minutes. Reduce heat if onions begin to stick or brown too fast. Remove from heat and keep warm until assembly.

In a small bowl combine 3 tbsp prepared horseradish, 1/2 cup sour cream, 2 tbsp mayonnaise, 1 tsp fresh lemon juice, 1 tsp Dijon mustard, 1/4 tsp salt and 1/8 tsp black pepper.

Stir until smooth and taste. Adjust horseradish for heat (increase in 1/2-tbsp increments) or salt/acid as needed. Chill until ready to use; flavors meld in 15–30 minutes but can be used immediately.

After searing the beef, keep the skillet over medium heat (do not wipe it clean). Add 1 tsp butter and the finely chopped shallot plus 1 minced garlic clove. Sauté 1–2 minutes until softened and fragrant, scraping browned bits (fond) from the pan with a wooden spoon.

Deglaze with 1/4 cup dry red wine, scraping the fond; simmer until wine is reduced by half, about 1–2 minutes. (If not using wine, skip this step and add beef stock directly.)

Add 1 cup beef stock, 1 tsp Worcestershire sauce, and 1 tsp fresh thyme (or 1/4 tsp dried). Bring to a gentle simmer and reduce slightly for 3–5 minutes until flavors concentrate. Taste and season with 1/4 tsp salt and 1/8 tsp black pepper as needed.

Strain the sauce through a fine-mesh sieve into a small saucepan or bowl to remove solids for a smooth au jus. Keep warm. Optionally whisk in an extra 1 tsp cold butter for shine just before serving.

Serve the au jus warm alongside the sliced beef for dipping or lightly drizzle over the assembled sandwich.