Brown the beef: In a large skillet or frying pan, melt butter or heat olive oil over medium heat. Add beef strips and cook over high heat until well browned. Remove and set aside.
Saute the Vegetables: In a large skillet, sauté onions, garlic and mushrooms until soft and golden brown and fragrant.
Make the Sauce: Add beef broth, dijon mustard and paprika. Stir together and allow to simmer for 5 minutes, until thickened slightly.
Add Sour Cream: Lower the heat and mix in sour cream. Stir gently until the sauce turns creamy and smooth without curdling.
Combine and Finish: Return the beef to the skillet. Mix everything together and cook for another 5 minutes. Garnish with parsley.
Serve: Serve hot over cauliflower rice, zoodles, or shirataki noodles for a hearty keto meal.
