A great accompaniment to Middle Eastern type sandwiches. Sumac can be purchased ground, or as whole berries you can grind yourself. It can be found at Middle Eastern groceries, and sometimes at well-stocked regular grocery stores. If you can't find sumac in your area, you can substitute with a little bit of paprika, cayenne and lemon juice instead. Untried by me, posted for ZWT NA*ME. From "It's All American Food" by David Rosengarten.