Sumac
Sumac, this spice comes from the berries of a wild bush that grows wild in all Mediterranean areas, especially in Sicily and southern Italy, and parts of the Middle East, notably Iran. It is an essential ingredient in Arabic cooking, being preferred to lemon for sourness and astringency. Many other varieties of sumac occur in temperate regions of the world. In North America Rhus glabra is known for its use in the tanning industry and for its medicinal properties. Also in North America is the related Rhus toxicodendron (poison ivy) which can cause a severe skin reaction when touched. Is often used as a souring agent in place of lemon juice, vinegar, or tamarind. Sumac is the spice of choice to add a tangy flavor to dishes. Most serious cooks would agree that there really is no substitute.
Sumac is used widely in cookery in Arabia, Turkey and the Levant, and especially in Lebanese cuisine. In these areas it is a major souring agent, used where other regions would employ lemon, tamarind or vinegar. It is rubbed on to kebabs before grilling and may be used in this way with fish or chicken. The juice extracted from sumac is popular in salad dressings and marinades and the powdered form is used in stews and vegetable and chicken casseroles. A mixture of yogurt and sumac is often served with kebabs. Zather is a blend of sumac and thyme use to flavor labni, a cream cheese made from yogurt.