Plomeek soup or broth is a Vulcan food that is described as bland in taste.
In 2151 Crewman Elizabeth Cutler tried it to impress T'Pol. (ENT: Strange New World)
In 2267 Nurse Christine Chapel made the mistake of serving it to Spock during his pon farr. Spock tossed the bowl at her, causing a public scene. (TOS: Amok Time)
In 2370 it was again used to impress a Vulcan, the Ferengi Quark added it to a meal for the Maquis member Sakonna. (DS9: The Maquis, Part I)
Onboard USS Voyager, Neelix once tried to make an authentic plomeek soup for Tuvok, although Tuvok found it too spicy.