Meanwhile, preheat the oven to 350º. In a large enameled cast-iron casserole, heat 2 tablespoons of the annatto oil. Season the chicken legs with salt and pepper; add to the casserole and cook over moderate heat, turning, until browned all over; transfer to a plate. Add the carrot, celery, shallot, leek, 2 sliced garlic cloves and half of the chopped onion to the casserole and cook, stirring, until softened. Add the wine, bring to a boil and cook until reduced by half. Add the tomato paste and cook, stirring, for 2 minutes. Stir in the stock, chicken legs and herb bundle and bring to a boil.