Bring a large pot of salted water to a boil. Add egg noodles and cook according to package instructions until al dente. Drain and set aside.

Slice beef sirloin into thin strips, about 1/4 inch thick and 2 inches long, cutting against the grain for maximum tenderness.

Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add half the beef strips in a single layer and cook for 2 to 3 minutes, stirring once or twice, until browned but still slightly pink inside. Remove to a plate and repeat with remaining beef.

In the same skillet, add remaining tablespoon of oil over medium heat. Add chopped onion and cook for 2 to 3 minutes until softened and translucent.

Add minced garlic and cook for 1 minute, stirring constantly, until fragrant.

Stir in sliced mushrooms and cook for about 5 minutes, stirring occasionally, until they've released their moisture and started to brown.

Sprinkle flour over the mushroom mixture and stir well to coat everything. Cook for 1 minute to remove raw flour taste.

Gradually pour in beef broth while stirring constantly to prevent lumps. Add Worcestershire sauce and stir to combine.

Let sauce simmer for about 5 minutes, stirring occasionally, until it thickens enough to coat the back of a spoon.

Reduce heat to low and stir in sour cream until completely incorporated and sauce turns creamy. Keep heat low to prevent sour cream from separating.

Return beef and any accumulated juices to the skillet. Stir gently to coat with sauce and let warm through for 2 to 3 minutes. Season with salt and pepper to taste.

Serve stroganoff over cooked egg noodles or alongside them. Garnish with freshly chopped parsley.