Satok is the Vulcan Minister of Security who reveals to the Enterprise-D that the mercenary Tallera is not a government agent but a member of an isolationist movement, in Gambit, Part II.
Satok appears in the seventh-season episode Gambit, Part II. Aboard a mercenary ship, the Romulan-looking Tallera has told Jean-Luc Picard that she is really T'Paal, an operative of the V'Shar, Vulcan's security service, working to stop the reassembly of an ancient psionic weapon, the Stone of Gol.
When the Enterprise contacts Vulcan to check, Minister Satok has a different account. No such agent has been assigned, and the woman is known to belong to a radical group that wants Vulcan isolated from other worlds.
His information tells the crew that the resonator is about to fall into exactly the wrong hands, and sends them to the planet in time to see Picard defeat it by emptying his mind of hostile thought.