01 - Bring a large pot of salted water to a boil. Cook the egg noodles following package directions until al dente. Drain and toss with a small amount of butter to prevent sticking. Set aside.
02 - Season the thinly sliced beef 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 the beef in batches and sear quickly until browned, about 1 minute per side. Remove beef and set aside.
04 - Add the remaining butter and olive oil to the skillet. Sauté the chopped onions for 2 to 3 minutes until softened. Add sliced mushrooms and cook until tender and browned, approximately 5 minutes. Stir in minced garlic and cook for 1 more minute.
05 - Sprinkle the all-purpose flour over the vegetable mixture and stir well to coat. Cook for 1 minute to remove the raw flour taste.
06 - Gradually pour in the low-sodium beef broth while stirring constantly to prevent lumps. Incorporate Worcestershire sauce, Dijon mustard, and paprika. Simmer the sauce for 3 to 4 minutes until it thickens.
07 - Reduce heat to low. Stir in sour cream until fully blended and warmed through. Return the seared beef along with any accumulated juices to the skillet. Gently cook for 2 to 3 minutes without boiling to avoid curdling.
08 - Adjust seasoning as necessary. Serve the beef and mushroom sauce over the prepared egg noodles, garnished with freshly chopped parsley.