Cut the stems off even with the leaves; remove the hardest bottom leaves, and cut off the top ones straight across, leaving an opening. Take out the inside, or choke. Wash well, and place upside down to drain. Put them into boiling water for half an hour, or until the leaves pull out easily; drain well, and serve on a napkin. They should be cut with a sharp knife into halves or quarters, and served with white, Bechamel, or Hollandaise sauce. The bottom and the base of the leaves only are eatable.