Ground sumac is used widely in Turkey, the Middle East, Syria and Lebanon as a "souring agent". Ground sumac's flavor is similar to lemon juice or vinegar: sour, fruity and astringent, but milder and less acidic than lemon.
Ground sumac comes from the dried purplish drupes [fruits] of a variety of sumac tree that grows wild from the Mediterranean through the Middle East region. Ground sumac is an unfortunate cousin to North America's misery, poison sumac [which has white drupes]. The use of ground sumac in cooking dates back to the Ancient Romans, who used it to add a sour tinge to their cooking. Sumac was also used traditionally for reducing fever.
Throughout the Middle East, ground sumac is mixed with thyme and sesame seeds to make Za'atar, a ubiquitous tabletop condiment. In Arab cuisine, sumac is used as a garnish on mezze dishes like hummus, and in tabbouleh. Sumac flavors salad dressings, meats, rice dishes and kebobs.
Rub sumac into meats before grilling, or sprinkle on fish and chicken. For a zingy, tart tasting vegetable, incorporate sumac into potato, beet, and mixed bean salads. Substitute sumac in any recipe where you might squeeze fresh lemon juice.