01 - Combine beef strips with salt and black pepper, then toss evenly with flour to coat.
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 onions for 3 minutes until translucent, then add mushrooms and cook 5-7 minutes until softened and golden.
04 - Stir in minced garlic and tomato paste; cook for 1 minute to blend flavors.
05 - Pour in beef broth, scraping up browned bits from skillet. Bring to a simmer and reduce for 3-4 minutes.
06 - Reduce heat. Stir in sour cream, Dijon mustard, and Worcestershire sauce until smooth. Return beef and juices to skillet. Simmer gently 2-3 minutes without boiling. Adjust seasoning with salt and pepper.
07 - Prepare egg noodles according to package instructions. Drain thoroughly.
08 - Plate noodles and top with beef and mushroom gravy. Garnish with chopped parsley before serving.