Bonjour James, I do believe you are correct as «fraise» is a feminine noun. Perhaps this is one that Aurélie needs to respond to in case there is a grammar rule that I am unaware of that would make this an exception. Note that l'un/l'une agrees in gender with the object it refers to. Ni l'un/e ni l'autre can also be used on its own to express neither: Tu veux fraise ou vanille? - Ni l'un ni l'autre. Do you want strawberry or vanilla? - Neither. Bonne chance !

Thanks Ron, I would assume that if one of the subjects had been masculine, then it would be Ni l`un..., but both are feminine.