Creamy Chicken Stroganoff

Heat the oil and butter in a large, deep frying pan and cook pancetta until it is crispy, then remove and set aside. Add the chicken in batches, and brown on all sides, then remove and set aside. Add the mushrooms and cook 8-10 minutes then remove and set aside. Add the onion, season well with salt and pepper and cook over a lower heat for 10 minutes then add the garlic and cook a further 2 minutes. Add the flour, stir well and cook for 2 minutes, then add the white wine, chicken stock, mustard, tomato paste and bay leaf. Return the pancetta, chicken and mushrooms back to the pan, bring everything to a boil and then reduce to a simmer, add the sour cream and cook uncovered for 15 minutes or until the sauce is thickened to a desired consistency and the chicken cooked through.