Sumac comes from the fruit of a bush indigenous to the Middle East. The bush is actually a member of the cashew family and the fruit is used widely in Turkey and other Arabic countries. Sumac is a main ingredient in the Middle Eastern spice blend Za'atar.
Before the Romans learned of lemons, they used sumac for its sour and pleasantly astringent taste. They called it Syrian sumac.
Sumac berries are picked, dried and ground into a coarse powder before being used in the cooking process. This powder is used to flavor salad dressings, meats, rice dishes and kebobs. Sumac can also be mixed with other vegetables such as onions and used as a condiment.