Season beef sirloin steak strips with salt and pepper.
Heat a large skillet over high heat and add 1 tbsp of olive oil.
Sear half of the steak strips for 30 seconds on each side, then promptly remove them from the skillet. Repeat with the remaining olive oil and steak strips.
Add 2 tbsp of butter to the empty skillet and add in the onions. Cook for 1 minute, then add in the mushrooms. Cook until tender, about 5 minutes.
Stir in garlic powder, flour, and paprika, stirring until thickened, approximately 1 minute.
Splash in the dry sherry, scraping off any browned bits on the bottom of the pan, and cook until the liquid is evaporated.
Gradually stir in the beef broth, then whisk in the sour cream and stir until combined and the sauce begins to thicken.
Add the seared steak strips and any plate juices back to the skillet and remove from heat.
Garnish with freshly chopped parsley and serve over hot cooked egg noodles. Enjoy!