My first impression upon reading the word "gherkin" was that that was BE, because I have never used or seen that word used in the U.S. Nevertheless, I suppose the word "gherkin" can be used in AE as well as BE, especially by those in the know.
In any case, besides gherkin fan
and fanned pickle
you can also findpickle fan
(although you have to be careful not to confuse that with a fan of pickles)
out there, so I guess the best solution is to choose whatever works best for your audience.