Board Thread:Boruto Discussions/@comment-27639227-20161015120521/@comment-25122992-20161015121201

Well, in volume 1 of the Boruto manga there were given the profiles of the main characters with their natures and techniques, where Yin Release is listed among Sarada's elements along with Lightning (which she also never displayed in the series).

But personally, I don't find it surprising, since Sharingan wielders often have an affinity to genjustu which falls into Yin Release category, although Sarada has never shown genjutsu use yet.