Perhaps the best known cold pureed soup, vichyssoise is a simple puree of potato and leeks that is traditionally enriched with cream; adding a bit of buttermilk along with the cream gives this version a pleasant tangy flavor. Here, leeks serve as both an aromatic, replacing the onion, as well as one of the base vegetables. Garlic is typically not used. The amount of stock or water called for is also reduced, since both cream and buttermilk are added. If making the soup for company, buy an extra leek to prepare the Leek Frisée (page 75) for the garnish.

Ingredients

　　FOLLOW THE BASIC RECIPE, sweating 3 medium leeks, white and pale-green parts only cut into 1/2-inch-thick half-moons (2 1/4 cups) and washed well (page 32), for aromatics, then adding 1 1/2 pounds russet potatoes (2 large), peeled and cut into 1-inch chunks (4 cups), for the base vegetable, and 3 1/2 cups stock or water. Proceed with recipe, simmering for about 15 minutes, then remove from heat. Puree, then add 3/4 cup each heavy cream and buttermilk. Thin with water or stock to reach desired consistency. Cool soup completely before refrigerating in an airtight container, up to 3 days; thin with stock or water as necessary before serving.

　　Reprinted with permission from Martha Stewart's Cooking School: Lessons and Recipes for the Home Cook by Martha Stewart. Copyright © 2008 by Martha Stewart. Published by Crown Publishing. All Rights Reserved.Martha Stewart is the author of dozens of bestselling books on cooking, entertaining, gardening, weddings, and decorating. She is the host of The Martha Stewart Show, the Emmy-winning, daily national syndicated program, and founder of Martha Stewart Living Omnimedia, which publishes several magazines, including Martha Stewart Living; produces Martha Stewart Living Radio, channel 112 on SIRIUS Satellite Radio; and provides a wealth of ideas and information on www.marthastewart.com.