As new markets demand the highest-quality olive oil, production can't keep up with demand, and the potential for fraud increases. Only ten years ago, Italy, Spain, and Greece consumed 90 percent of the worldwide market; now they are down to 60 percent, with consumption rising in Japan, South America, and the U.S. Unaprol, the association of Italian olive oil producers, in conjunction with Gambero Rosso, the publishing concern behind one of Italy's foremost wine and food guides, will put out a comprehensive handbook in 2011 listing the highest-quality extra-virgin olive oils. However, until that comes out, choose the oil as you do wine. There are hundreds of varieties of olives, and single varietals are prized. It's important to trust your vendor and read the label. Look for clues to where the olives come from and whether it's an estate-bottled oil. Lastly, develop your taste buds. For your next dinner party suggest that each of your guests bring a bottle of premium olive oil. Boil, peel, and slice some red potatoes (bread has flavor; potatoes are used because they act as a more neutral base), and serve the potatoes as an antipasto. You and your guests will have fun discovering some previously unknown oils, and you'll learn what appeals to you. In the end it really is the taste that matters.