Place well-cleaned asparagus in a glazed earthenware jug. Add enough salt to the water to support a raw egg, that is, use 1 glass salt for 3–4 glasses water. Bring this salted water to a boil and cover asparagus completely with the boiling liquid. Let the water cool, wrap and tie a paper moistened with olive oil round the jug and tie a bladder over the paper. Two hours before using, soak the asparagus in cold water and boil in a large quantity of water.