Ingredients
Method
- Slice the beef sirloin into thin strips perpendicular to the grain and season generously with salt and pepper.
- Heat two tablespoons of butter in a large skillet over medium-high heat.
- Sear the beef strips in batches until browned, then remove and set aside.
- Add the remaining butter to the skillet and sauté the mushrooms until golden brown.
- Add the diced onions to the mushrooms and cook until translucent and soft.
- Stir in the flour and cook for one minute to form a light roux.
- Slowly pour in the beef broth and Worcestershire sauce, scraping the bottom of the skillet to release browned bits.
- Simmer the sauce until thickened, then stir in the seared beef and any accumulated juices.
- Remove from heat and stir in the room-temperature sour cream until well combined and creamy.
Notes
Ensure the sour cream is at room temperature before adding to the sauce to prevent it from curdling. Serve over buttered egg noodles or mashed potatoes for the most authentic experience.