Bring a large pot of water to a boil and cook the egg noodles according to package instructions. Drain and set aside.
In a large skillet, heat olive oil over medium heat. Add diced onion and minced garlic. Sauté for about 3-4 minutes until the onion is translucent.
Add the ground beef to the skillet, breaking it apart with a spoon. Cook until browned, about 5-7 minutes. Season with salt and pepper.
Stir in the sliced mushrooms and cook for an additional 5 minutes until the mushrooms soften.
In a bowl, combine beef broth, Worcestershire sauce, Dijon mustard, and flour. Whisk until smooth. Pour this mixture into the skillet with the beef and mushrooms. Stir well and cook for another 3-4 minutes.
Reduce the heat to low and mix in the sour cream. Stir until well combined and heated through, but do not let it boil. Adjust seasoning with salt and pepper as needed.
Place the cooked noodles on plates and top them with the beef stroganoff mixture. Garnish with fresh parsley if desired.