01 - Season 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, approximately 5–7 minutes. Transfer to a plate and cover to keep warm.
03 - Add remaining 1 tbsp butter to the same 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 until fragrant.
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 to prevent lumps. Add Dijon mustard, paprika, and Worcestershire sauce. Simmer for 3–4 minutes until sauce thickens slightly.
06 - Reduce heat to low. Stir in sour cream until fully incorporated and smooth. Return chicken and accumulated juices to skillet. Simmer gently for 2–3 minutes until heated through. Do not boil to prevent curdling.
07 - Taste and adjust seasoning as needed. Garnish with fresh parsley and serve hot over egg noodles, rice, or mashed potatoes.