Steps

• Begin by ensuring all your ingredients are ready for cooking. Slice the beef sirloin into thin strips, finely chop the onion, and mince the garlic.
• Heat the olive oil in a large skillet. Add the beef strips in batches, searing them to brown on all sides before removing and setting aside.
• In the same skillet, add more olive oil if needed. Sauté the onions until translucent, then add the garlic and mushrooms, stirring slowly.
• Sprinkle flour over the vegetables and whisk in the beef broth gradually, allowing the sauce to thicken over a gentle heat.
• Lower the heat and stir in the sour cream until fully incorporated into the sauce.
• Return the beef strips to the skillet, cover, and let simmer on low heat for about 10 minutes.
• Season with salt and pepper to taste, garnish with parsley, and serve hot over egg noodles, rice, or mashed potatoes.