Put the chicken pieces into a heavy casserole with the stock, bring to a boil, reduce the heat, and simmer gently, covered, for 45 minutes, or until tender. Lift the chicken out onto a platter and set aside. Pour the stock into a jug. Rinse out and dry the casserole.
In a blender or food processor combine the onion, garlic, parsley, coriander, lettuce, hot peppers, and almonds, and reduce to a coarse puree. Do not over blend as the finished sauce should have some texture, not be entirely smooth. Heat the oil or lard in a large, heavy skillet and pour in the puree, which will be almost paste like because of the almonds. Cook the mixture, stirring constantly with a wooden spoon, for 3 to 4 minutes over moderate heat. Transfer it to a casserole. Stir in 2 cups of the stock, season to taste with salt. Add the chicken pieces, cover, and simmer just long enough to heat the chicken through. Serves 6.
Arroz Blanco (White Rice) is good with this. For a completely Mexican meal, serve the chicken with the rice and with tortillas. Frijoles (Beans), and guacamole (Avocado Sauce).