Cook Pasta : Boil a large pot of salted water and cook egg noodles according to package directions until al dente. Drain and set aside.

Prepare the Beef : Heat olive oil or butter in a large skillet over medium-high heat. Add beef slices in batches and sear until browned but not fully cooked. Remove beef from skillet and set aside.

Sauté Vegetables : In the same skillet, add chopped onions and garlic; cook 2–3 minutes until softened. Add sliced mushrooms and cook until tender and lightly browned, about 5 minutes.

Make the Sauce : Sprinkle flour over the mushrooms and stir to coat (optional, for thickening). Add beef broth and Dijon mustard, scraping up any browned bits from the pan. Simmer for 3–5 minutes until slightly thickened.

Finish the Stroganoff : Lower heat to medium-low. Stir in sour cream until smooth. Return beef to the pan and cook for 2–3 minutes until heated through. Season with salt, pepper, and paprika.

Combine with Pasta :Toss cooked pasta with beef stroganoff sauce until well coated.

Serve : Divide into bowls or plates. Garnish with fresh chopped parsley and additional paprika if desired. Serve hot.