01 - Bring a large pot of salted water to a boil. Cook egg noodles according to package instructions. Drain and toss with a little butter to prevent sticking. Set aside.
02 - Season beef strips with salt and freshly ground black pepper evenly.
03 - Heat 1 tablespoon butter and 1 tablespoon olive oil in a large skillet over medium-high heat. Add beef in batches and sear quickly until browned, about 1 minute per side. 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 browned, approximately 5 minutes. Stir in garlic and cook for another minute.
05 - Sprinkle flour over the vegetables and stir to coat. Cook for 1 minute to eliminate raw flour taste.
06 - Gradually add beef broth, stirring constantly to avoid lumps. Incorporate Worcestershire sauce, Dijon mustard, and paprika. Simmer for 3 to 4 minutes until sauce thickens.
07 - Reduce heat to low; stir in sour cream until smooth and warmed through. Return seared beef along with juices to the skillet. Cook gently for 2 to 3 minutes, avoiding boiling to prevent curdling.
08 - Adjust seasoning as needed. Serve beef and sauce over warm egg noodles. Garnish with fresh parsley.