Wash and pare potatoes, leaving on the skin if possible (especially if potatoes are fresh out of the ground). Cut into morsels so they will cook quickly, peel and pare an onion, add bay leaves, salt and pepper, and cover just barely with water. Bring to a boil and lower heat so that the tubers will simmer until tender to the fork. Mash, then add butter and grated truffles. Serve with filet mignon, pork chops, or summer ratatouille.