01 - Season beef strips with salt and black pepper, then toss evenly with flour.
02 - Heat 1 tbsp butter and olive oil in a large skillet over medium-high heat. Add beef in batches and sear 1-2 minutes per side until browned. Remove and set aside.
03 - Add remaining 1 tbsp butter to skillet. Sauté chopped onion until translucent, about 3 minutes. Add mushrooms and cook 5-7 minutes until softened and golden.
04 - Stir in minced garlic and tomato paste; cook for 1 minute to release flavors.
05 - Pour in beef broth, deglazing skillet and scraping up browned bits. Simmer 3-4 minutes to reduce slightly.
06 - Lower heat. Stir in sour cream, Dijon mustard, and Worcestershire sauce until smooth. Return beef and juices to skillet; simmer gently for 2-3 minutes without boiling. Adjust salt and pepper to taste.
07 - Cook egg noodles according to package instructions. Drain thoroughly.
08 - Serve beef stroganoff atop noodles and garnish liberally with chopped fresh parsley.