Bring a large pot of salted water to a boil. Cook egg noodles according to package instructions until al dente. Drain and set aside.
In a medium bowl, season the beef strips with salt and black pepper. Sprinkle the flour over the beef and toss to coat evenly.
Heat 1 tablespoon of butter and the olive oil in a large skillet over medium-high heat. Add the beef strips in a single layer and cook for 2-3 minutes per side until browned but not cooked through. Remove beef from skillet and set aside.
In the same skillet, add the remaining 1 tablespoon of butter. Add the chopped onion and cook for 3-4 minutes until softened.
Add the sliced mushrooms and cook for 5-6 minutes until they release their moisture and start to brown.
Stir in the minced garlic and cook for 30 seconds until fragrant.
Pour in the beef broth, Worcestershire sauce, and Dijon mustard. Stir to combine and bring to a simmer.
Return the beef along with any accumulated juices to the skillet. Cook for 3-4 minutes until the beef is cooked through and the sauce has slightly thickened.
Remove the skillet from heat and stir in the sour cream until fully incorporated. Do not boil after adding sour cream to prevent curdling.
Serve the beef stroganoff over the cooked egg noodles and garnish with chopped fresh parsley.