Sorrel Soup

Schav is a cold sorrel soup prized by Jews of Eastern Europe. (My grandparents would eat it several times a week in the summer.) I grew up on bottled schav because the main ingredient—a tart spinachy-looking leaf called sorrel—wasn’t available in the United States. (The first time I tasted a fresh sorrel soup was at the La Varenne Cooking School in Paris.) Today, you can buy fresh sorrel at a gourmet shop or specialty greengrocer. If you can’t find it, an interesting, not strictly tradition