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