Pat beef slices dry and season with salt, pepper, and paprika.
Heat olive oil and 1 tablespoon butter in a large skillet over high heat. Sear beef in batches for 60–90 seconds per side until browned. Transfer to a plate.
Add 1 tablespoon butter to the skillet. Cook mushrooms for 4–5 minutes until golden. Add onion and cook 3 minutes. Add garlic and cook 30 seconds.
Sprinkle flour over vegetables and stir for 1 minute. Slowly pour in beef broth while stirring. Add Worcestershire sauce and Dijon mustard. Simmer 3–4 minutes until thickened.
Reduce heat to low. Stir in sour cream until smooth. Return beef and any juices to the skillet. Simmer gently for 2–3 minutes.
Cook egg noodles according to package directions. Drain and toss with remaining 1 tablespoon butter.
Serve stroganoff over egg noodles and garnish with fresh parsley.
