Bring a large pot of salted water to a rolling boil and cook the egg noodles according to package directions until al dente (tender but still slightly firm), about 8-10 minutes. Drain well and set aside, tossing with butter if desired.

Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the beef strips in a single layer and sear for 3-4 minutes until browned with golden edges. Remove and set aside.

Add the remaining tablespoon of olive oil to the same skillet. Sauté the chopped onion for 2-3 minutes until softened, then add the minced garlic and cook for another minute until fragrant.

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

Sprinkle the flour over the mushroom mixture and stir continuously for about 1 minute to cook out the raw flour taste.

Gradually pour in the beef broth and Worcestershire sauce, stirring constantly to prevent lumps. Let the mixture simmer for 2-3 minutes until it thickens and coats the back of a spoon.

Reduce the heat to low and stir in the sour cream until completely smooth. Cook for another 2 minutes without boiling. Season generously with salt and pepper to taste.

Return the seared beef to the skillet along with any accumulated juices, stirring gently to coat everything in the sauce. Heat through for 2 minutes, then serve immediately over the prepared noodles and garnish with fresh parsley.