Cook the Egg Noodles:

1. Boil the Noodles: Bring a large pot of salted water to a boil. Add the egg noodles and cook according to the package instructions until al dente, about 8-10 minutes. Drain and set aside.

Prepare the Beef and Sauce:

2. Cook the Beef: Heat olive oil or butter in a large skillet over medium-high heat. Add the beef strips in a single layer, cooking for 2-3 minutes per side until browned and just cooked through. Remove the beef from the skillet and set it aside.
3. Sauté the Vegetables: In the same skillet, add the chopped onions and garlic. Cook, stirring occasionally, until softened and fragrant, about 2 minutes. Add the sliced mushrooms and cook for another 3-4 minutes, until the mushrooms release their moisture and become tender.
4. Deglaze the Pan: Add the beef broth to the pan, stirring to scrape up any browned bits from the bottom of the skillet. Stir in the Worcestershire sauce and Dijon mustard. Let the mixture simmer for 3-4 minutes until the sauce has reduced slightly.
5. Add the Sour Cream: Reduce the heat to low and stir in the sour cream. Cook for another 2-3 minutes, stirring occasionally, until the sauce is smooth and creamy. Season with salt and pepper to taste.

Combine and Serve:

6. Return the Beef to the Skillet: Add the cooked beef back into the skillet, stirring to combine. Cook for another 2-3 minutes until the beef is heated through and coated in the sauce.
7. Serve the Beef Stroganoff: Serve the creamy beef mixture over the cooked egg noodles. Garnish with fresh parsley if desired.