Meanwhile, in a large saucepan
, heat the oil. Add the hearts, gizzards, wing joints and necks and season with salt and pepper. Cook over moderately high heat, stirring, until richly browned, 10 minutes. Add the carrots, tomatoes, celery, leek, onion, garlic, bay leaves and thyme and cook, stirring, until softened, 5 minutes. Stir in the flour and tomato paste
, then gradually stir in the stock and wine. Bring to a boil, stirring, then reduce the heat to moderately low and simmer for 1 hour. Strain the sauce into a bowl, pressing on the solids.