Elisabeth Luard explains the many uses of a versatile alternative to the lemon
The berries of sumac, a small shrub-like tree, Rhus coriaria, common in British gardens, are used as a souring agent in regions where lemons can’t be grown. Native to the mountains of Lebanon and Syria, the variety most widely planted in English gardens for its exuberant autumn leaf colour is R typhina, staghorn sumac, while a New World species, R glabra, was used by Native Americans to prepare a refreshing drink.
The berries of all three varieties* can be prepared in infusion or dried and ground to a powder. Gather on a dry day when the berries are fully ripe and use them fresh or dried. To dry, strip the berries from their stalks, spread on clean newspaper and leave in warm airy corner till they look like little crimson peppercorns, the form in which they can be used in infusion or milled to a powder for sprinkling.
To prepare fresh berries as an infusion, mash whole clusters roughly in a bowl, cover with cold water and leave to soak for 10-15 minutes till the liquid is thoroughly soured and turned blush-pink. The flavour is sour-apple rather than citric: more delicate than lemon juice and less aggressive than vinegar (good in a fish soup).
For a refreshing drink or to freeze as a sorbet, sweeten with honey or sugar syrup. Finish savoury dishes with a dash of undiluted sumac water, much as you would witha squeeze of lemon. In the Lebanon and throughout the Middle East, dried, powdered sumac is the diagnostic ingredient – along with thyme, salt and toasted sesameseeds – in za’atar, a flavouring dip eaten with pitta or used as a finishing sprinkle, as followers of Ottolenghi won’t need reminding.
*Hazard warning: take care to avoid Toxicodendron vernix, known as poison sumac, a different species which has loose strings of smooth, white berries rather than the dense, torpedo-shaped clusters of tiny, hairy,scarlet berries of sumac proper.