how season cast iron skillet?
['Scrub skillet well in hot soapy water.', 'Dry thoroughly.', 'Spread a thin layer of melted shortening or vegetable oil over the skillet.', 'Place it upside down on a middle oven rack at 375°. (Place foil on a lower rack to catch drips.)', 'Bake 1 hour; let cool in the oven.']