Truffles are best when fresh, but unlike anything else except pastry, meat and fish essences, and ice cream, they do very satisfyingly well when frozen. While they are at their peak of freshness, wrap each truffle separately in two layers of odorless plastic wrap, then in aluminum foil, and put in a sealed, dated container in the freezer. The secret to using frozen truffles is to put them in whatever they are flavoring while still frozen and leave them there for an hour or two, for maximum flavor penetration. Only in this way do the truffles retain their crisp texture and their flavor, and impart all their perfume to what surrounds them. Truffles preserved in Madeira make superb truffle-flavored liquid but soft truffles. Canned truffles are a total waste of money. Despite their reputation, truffles are not expensive when used effectively. A whole egg-size black truffle, costing twenty to thirty dollars, will provide six people with a special-occasion feast they will never forget.