Vulcan brandy was an alcoholic beverage produced by the Vulcans, the liquor being a pale amber in hue.
In 2377, after several Maquis crew members commandeered the USS Voyager (under the influence of Teero Anaydis' mind control), Chakotay and Tuvok shared a brief drink of Vulcan brandy before Chakotay tested Tuvok's loyalty to the Maquis by ordering him to fire a phaser at Captain Janeway (with nothing happening, as the phaser was in actuality defective). (VOY: "Repression")
Background
The existence of a Vulcan alcoholic drink would seem most curiously to contradict a previous statement set forth by Spock in TOS: "The Conscience of the King", where he states: "My father's race was spared the dubious benefits of alcohol," when offered a glass of Saurian brandy by Dr. McCoy. Preceding this remark, T'Pol specifically notes in ENT: "Breaking the Ice" the Vulcan stance on abstaining from alcohol, in that case wine. Cultural aversion to alcohol on the part of the Vulcans may have dissolved by the 24th century, given that in 2370 Sakonna drank a glass of Ferengi red wine with Quark. (DS9: "The Maquis, Part I")