In book two of Evil Librarians, Alcatraz says he once "...jokingly dubbed my potato a 'Potin Potato, grown and crafted in the fields of Potallia',". He says that the Crystallians were not amused, and that he should've used his carrot.
Direct "Potato in a minefield" Reckoners referece.
That or Brandon Sanderson thinks carrots are more romantic than potatoes.