1. Cook egg noodles according to package instructions. Drain and set aside.
2. Heat 1 tbsp olive oil in a large skillet over medium-high heat. Sear the beef slices for 2-3 minutes until browned. Remove and set aside.
3. In the same skillet, add remaining oil and sauté onions, mushrooms, and garlic until softened, about 5 minutes.
4. Sprinkle flour over the vegetables and stir well. Slowly pour in beef broth, stirring to avoid lumps, and let it simmer until slightly thickened.
5. Lower the heat and stir in sour cream, Dijon mustard, and season with salt and pepper. Return the beef to the skillet and cook for 2-3 minutes until warmed through.
6. Serve the beef and sauce over the egg noodles, garnished with fresh parsley.