Mastic

Mastic is a resin harvested specifically from the mastic tree grown on the Greek island of Chios, and nowhere else produces it in commercially meaningful quantity, which makes it one of the truly geography-locked ingredients in Greek cooking. The trees are cut in summer and the resin weeps out and hardens into small tear-shaped pieces, historically valuable enough that medieval Chios paid part of its taxes to Constantinople in mastic.

In the kitchen it is crushed with a little sugar, which stops it clumping into a sticky mass, and worked into doughs and puddings where it contributes both a faint piney, resinous aroma and a distinctive slightly chewy quality to the finished texture. Tsoureki, the Easter bread, and Cypriot loukoumia both use it for exactly that chew, alongside mahlepi.

It is sold as small hard tears, sometimes labelled by their Chios origin, and a little goes a long way: a pinch, crushed with sugar, is enough to flavour a full batch of bread dough or a tray of sweets.