01 - Bring a large pot of salted water to a boil. Cook egg noodles according to package directions. Drain and toss with a small amount of butter to prevent sticking. Set aside.
02 - Season the sliced beef with salt and freshly ground black pepper evenly.
03 - Heat 1 tablespoon butter and 1 tablespoon olive oil over medium-high heat in a large skillet. Add beef in batches and sear each side for about 1 minute until browned. Remove beef and set aside.
04 - Add remaining butter and olive oil to the skillet. Sauté onions for 2 to 3 minutes until softened. Add mushrooms and cook until tender and golden, approximately 5 minutes. Stir in garlic and cook for 1 additional minute.
05 - Sprinkle flour evenly over the vegetables and stir well to coat. Cook the mixture for 1 minute to eliminate raw flour taste.
06 - Gradually pour in beef broth while stirring constantly to avoid lumps. Add Worcestershire sauce, Dijon mustard, and paprika. Simmer the sauce for 3 to 4 minutes until thickened.
07 - Reduce heat to low and stir in sour cream until smooth and warmed through. Return seared beef and any accumulated juices to the skillet. Cook gently for 2 to 3 minutes without boiling to prevent curdling.
08 - Adjust seasoning to taste if needed. Plate the beef mixture over warm egg noodles and garnish with fresh parsley.