Start by boiling a large pot of salted water over high heat. Once boiling, add in your egg noodles and cook for about 8-10 minutes, stirring occasionally, until they are just al dente. Drain the noodles in a colander, allowing excess water to escape, then set aside while you prepare the sauce.

In a large skillet, heat 2 tablespoons of olive oil over medium-high heat until shimmering. Add the strips of beef sirloin in a single layer, sear for about 3-4 minutes until nicely caramelized, then remove from skillet.

In the same skillet, add another tablespoon of olive oil if needed, then toss in the sliced onions. Sauté for 2-3 minutes until they turn translucent, then add minced garlic and stir for about 1 minute until aromatic.

Add the sliced mushrooms to the skillet and cook for about 5 minutes, allowing them to soften and become golden brown.

Sprinkle all-purpose flour evenly over the mushroom and onion mixture, stirring vigorously. Cook for 1 minute to allow the flour to absorb flavors.

Gradually pour in the beef broth and add Worcestershire sauce, stirring continuously to avoid lumps. Raise heat slightly and bring to a gentle simmer, cooking for about 5 minutes until the sauce thickens.

Reduce heat to low and dollop in the sour cream, stirring gently until smooth. Heat for an additional 2 minutes then season with salt and pepper to taste.

Carefully return the seared beef back into the skillet and gently fold into the creamy sauce to heat through for about 2-3 minutes.

Serve immediately, mixing beef and sauce with reserved noodles or spooning over them. Garnish with freshly chopped parsley.