01 - Season the chicken strips evenly 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, about 5-7 minutes. Transfer to a plate and keep warm.
03 - Add remaining 1 tbsp butter to the pan. Sauté onion for 2-3 minutes until translucent. Add mushrooms and cook until browned and liquid has evaporated, about 5 minutes. Stir in garlic and cook for 1 minute.
04 - Sprinkle flour over vegetables, stirring constantly to coat evenly. Cook for 1 minute to remove raw flour taste.
05 - Gradually whisk in chicken broth while stirring. Add Dijon mustard, paprika, and Worcestershire sauce. Simmer for 3-4 minutes until slightly thickened.
06 - Reduce heat to low and stir in sour cream until fully incorporated. Do not boil to prevent curdling. Return chicken and any accumulated juices to the skillet.
07 - Simmer gently for 2-3 minutes until everything is heated through. Taste and adjust seasoning if needed.
08 - Garnish with fresh parsley and serve hot over egg noodles, rice, or mashed potatoes.