Vanilla was a flavor of ice cream that originated on Earth.
In 2151, Liana ate vanilla ice cream in Enterprise NX-01's mess hall. When Trip Tucker noted her choice, she was surprised, having been unaware that there were any other flavors. (ENT: "Oasis")
In 2153, while Enterprise was hosting a Vissian delegation, Tucker introduced Calla and Traistana to vanilla ice cream in a sundae. ENT: "Cogenitor")
In 2268, it was one of the many flavors requested by the children of the Starnes Exploration Party when Christine Chapel offered them ice cream. Steve O'Connel was disappointed when his "unpleasant surprise" turned out to be coconut and vanilla, both white. TOS: "And the Children Shall Lead")