Sumac trees (Rhus coriaria) grow wild in the Mediterranean region and are found in southern Italy and much of the Middle East, especially south-eastern Turkey and Iran. Sumac berries were used by the Romans, who referred to them as Syrian sumac. Lemons being unknown in Europe at that time, sumac was a pleasing souring agent, less sharp than vinegar and more agreeable than tamarind. Although related to the poison sumac tree that is grown as an ornamental for the bright crimson leaves of autumn, the culinary sumac is perfectly safe to consume.
Sumac berries stand out from the foliage like optimistic Christmas decorations. They are tightly bunched in conical clusters. Each berry — which develops from a similarly dense bunch of small, white flowers — is a little larger than a peppercorn, and when fully formed is green and covered with a hairy down like a kiwifruit. Most of the non-poisonous varieties of rhus have hairy berries, whereas the fruits on some decorative types are smooth. The berries then ripen to a pinkish red, and are finally deep crimson when harvested. Sumac berries have a very thin outer skin and flesh surrounding an extremely hard, tick-shaped seed.
The best quality sumac spice comes from the thin outer flesh that contains the greatest amount of malic acid (the same acid that occurs naturally in green apples). Ripe, freshly harvested berries are placed in a large crusher, that rubs the flesh off the small, hard, coriander seed-like seeds inside.
Sieving separates deep crimson particles of sumac from the crushed berry clusters leaving leaves, stems and seeds behind. In many cases the seeds are then ground, and either sold as a very pale sumac, or in the worst case scenarios mixed back in with decorticated flesh and artificially coloured. Beware of sumac powder that is very brightly coloured!
In the Middle East sumac is used extensively as a souring agent instead of lemon juice or vinegar. It is sprinkled on kebabs before cooking and garnishes salads, particularly those with tomatoes, parsley and onions. In fact the flavor of sumac complements tomatoes and avocados so well, we hardly ever consume either without it. Sumac is delicious on roast meats, especially lamb, mixed with paprika, pepper and oregano. Grilled fish and chicken are greatly enhanced by a light dusting of sumac prior to cooking. The Middle Eastern equivalent of mixed herbs, za’atar, is made by blending thyme, toasted sesame seeds, sumac, parsley, oregano and salt. Traditionally, za’atar is sprinkled on flatbread that has been brushed with olive oil and then lightly toasted.