Chios Mastic Gum, or “Mastiha”, as it is called in Greece, is the crystal resin of the craggy, gnarled “mastic-tree” (Pistacia Lentiscus var. Chia) and it is produced exclusively on the island of Chios, where it has been the source of much island wealth for thousands of years. Mastiha is one of the most mysterious substances, at once a spice, an incense and a medicine, proven to be beneficial to ulcers and other stomach ailments as well as to oral hygiene. As a spice it is unique because it is so versatile, insinuating itself with equal facility into sweet and savory dishes, and pairing beautifully with everything from citrus to tomatoes to chocolate to creams and yogurt. In order to use it one must crush it first in a mortar and pestle, either with a little salt (for savory dishes) or sugar (for sweet dishes). Keep it away from electric spice grinders.