New England-style Clam Chowder

Unlike an old-fashioned New England clam chowder, which is thickened with flour and enriched with heavy cream, ours is thickened with a puree of vegetables, and enriched with lowfat milk. In a pinch, canned or frozen chopped clams can be used in this recipe, but fresh ones are best. You can make the soup ahead, but it may need to be thinned slightly with a little more milk before serving.