Mushroom Sirloin Recipe

Prep and marinate

Pat the sirloin dry with paper towels. In a shallow dish or bowl, whisk together 2 tbsp olive oil, 1 tbsp soy sauce, 1 tsp Worcestershire sauce, 2 tsp minced garlic, 1 tsp black pepper and 1 tsp kosher salt. Place the steak in the mixture and coat both sides. Let sit at room temperature for 20–30 minutes (or refrigerate up to 4 hours; bring back to room temperature before cooking).

Bring to room temperature

Remove steak from refrigerator 30 minutes before cooking if chilled. Pat again to remove excess marinade (reserve marinade juices for basting if desired).

Heat a heavy skillet (cast iron preferred) over medium-high heat until very hot, about 3–5 minutes. Add a thin film of oil or a small knob of butter. Sear the steak 3–4 minutes per side for medium-rare (internal temp 130–135°F / 54–57°C), longer for desired doneness. If steak is thick, sear edges by holding with tongs. During final minute, baste with pan juices or reserved marinade. Transfer steak to a cutting board and tent loosely with foil; rest 8–10 minutes before slicing.

Sauté aromatics

While the steak rests, wipe out excess fat from the skillet leaving about 1 tbsp drippings. Add 2 tbsp unsalted butter and 1 tbsp olive oil over medium heat. When butter foams, add 1/2 cup finely chopped onion and sauté 3–4 minutes until translucent. Add 1 tsp minced garlic and cook 30 seconds until fragrant.

Cook mushrooms

Add 10 oz sliced cremini mushrooms and 1 tbsp fresh thyme leaves. Increase heat to medium-high and cook, stirring occasionally, until mushrooms release liquid and begin to brown, about 6–8 minutes.

Deglaze & make sauce

Pour 1 tbsp dry white wine (or beef broth) into the pan to deglaze, scraping browned bits from the bottom. Let reduce 1–2 minutes. Stir in 3 tbsp beef broth, 1 tsp Dijon mustard and 1 tsp all-purpose flour (sprinkled) to slightly thicken. Cook 1–2 minutes to blend. If using, stir in 2 tbsp heavy cream for richness. Season with 1/2 tsp salt and 1/2 tsp black pepper; taste and adjust.

Finish

Simmer the sauce 1–2 minutes until slightly thickened and glossy. Turn off heat and stir in 1 tbsp chopped fresh parsley and a squeeze of lemon if using to brighten flavors.

Slice the rested sirloin against the grain into 1/4-inch slices. Spoon the warm mushroom sauce over the sliced steak or serve on the side. Garnish with extra parsley. Serve immediately with chosen sides (mashed potatoes, roasted vegetables, or a simple salad).