How to Make It
Place the chilies in a small heavy skillet over very low heat. Toast, stirring constantly, until they make a hollow sound, 12 to 15 minutes; they should be brittle but only faintly darkened, not burned. Let cool slightly. Grind to a fine powder using an electric spice grinder or coffee grinder (or if you have one, a Mexican stone molcajete).
Season the chicken with salt and freshly ground black pepper. Heat the oil or lard in a large skillet over medium-high heat. Brown the chicken pieces until golden, 3 minutes on each side. Pour off any excess fat from the skillet and return to medium heat. Sprinkle the ground chilies and black pepper over the chicken and turn the pieces to coat evenly. Add the vinegar, butter, garlic and orange juice and scrape in the seeds of the vanilla bean. Cook, uncovered, for 15 to 20 minutes, or until the sharpness of the vinegar is mellowed and the chicken is cooked-through. Serve hot.