01 - Season the chicken strips thoroughly with salt and pepper on all sides.
02 - Heat 1 tbsp butter and olive oil in a large skillet over medium-high heat. Add chicken and sauté until golden and cooked through, approximately 5 to 7 minutes. Transfer to a plate and keep warm.
03 - Add remaining 1 tbsp butter to the pan. Sauté onion for 2 to 3 minutes until translucent. Add mushrooms and cook until browned and liquid has evaporated, about 5 minutes. Stir in garlic and cook 1 minute.
04 - Sprinkle flour over vegetables, stirring constantly to coat evenly. Cook for 1 minute to remove raw flour taste.
05 - Gradually pour in chicken broth while stirring continuously. Add Dijon mustard, paprika, and Worcestershire sauce. Simmer for 3 to 4 minutes until slightly thickened.
06 - Reduce heat and stir in sour cream until fully incorporated. Do not boil to prevent curdling. Return chicken and accumulated juices to the skillet. Simmer gently for 2 to 3 minutes until heated through.
07 - Taste the sauce and adjust salt and pepper as needed.
08 - Garnish with fresh parsley and serve hot over egg noodles, rice, or mashed potatoes.