Cook the Noodles:
Cook the egg noodles according to package instructions. Drain and set aside.

Brown the Beef:
Heat olive oil in a large skillet over medium-high heat. Add the sliced beef, season with salt and pepper, and cook until browned on both sides. Remove the beef from the skillet and set aside.

Sauté the Vegetables:
In the same skillet, melt the butter. Add the chopped onion and cook until soft and translucent, about 3–4 minutes. Add the garlic and cook for another 30 seconds until fragrant.

Cook the Mushrooms:
Toss in the sliced mushrooms and cook until tender and golden, about 5 minutes.

Make the Sauce:
Sprinkle the flour over the mushroom mixture and stir to coat. Cook for 1 minute to remove the raw flour taste. Gradually add the beef broth, stirring constantly to prevent lumps.

Add Flavor:
Stir in the Worcestershire sauce and Dijon mustard (if using). Simmer for 2–3 minutes until the sauce thickens.

Combine Everything:
Return the beef to the skillet and reduce heat to low. Stir in the sour cream and heat gently until everything is warmed through. Don’t let it boil, as the sour cream may curdle. Adjust seasoning with salt and pepper as needed.

Serve:
Spoon the beef stroganoff over the cooked egg noodles. Garnish with fresh parsley and serve warm.