cassis

Though not persuaded to go out and “taste the rainbow” and draw the comparison myself, I found it pretty interesting to learn that whereas purple coloured candies and drinks for American palettes might be conditioned to expect a grape taste (natural and artificial flavouring), for Europe and elsewhere, purple signals blackcurrant, as Atlas Obscura informs.
Although I had only ever heard of it as a fancy infusion for imported vodka, I think they are delicious—I might be a bit partial since it is called (Schwarze) Johannisbeere in Germany—and are kind of a super-food. The shrubs were kept out of the Americas for a long time because it was thought that they carried botanical disease agents, but the moratorium is being relaxed because there’s little scientific evidence of this correlation. “Grape-Drank” might no longer be the default for those in the States.