Watercress sandwich

Watercresses are semi-aquatic plants native to Earth, one of the oldest known leaf vegetables consumed by humans. Watercress is traditionally consumed in sandwiches.

Watercress sandwiches were a favorite of Admiral Alynna Nechayev, and were part of a "peace offering" made to her by Captain Jean-Luc Picard during the admiral's visit to the USS Enterprise (NCC-1701-D) in 2370. 

Likewise, Nechayev offered watercress sandwiches to Picard when he visited Starfleet Command in 2380, again as a form of peace offering.