Mix all ingredients in small bowl. DO AHEAD: Can be made 8 hours ahead. Cover; chill. A thick yogurt; sold at some supermarkets and at specialty foods stores (such as Trader Joe`s and Whole Foods markets) and Greek markets. If unavailable, place 1 quart regular plain yogurt in cheesecloth-lined strainer set over large bowl. Cover and chill overnight to drain. ** A flavoring extract; available in the liquor aisle or baking section of some supermarkets and at liquor stores and Middle Eastern markets.