I use corn starch to keep marshmallows dry but I need a replacement, can't be potato either. Help!
How about tapioca starch?
i use arrow root (powdered...) when i do homemade cake flour in place of cornstarch and it works very well! it could work here?
For marshmallows, I've tried arrowroot powder, cocoa powder (personal favorite), and ...oh, what's that other starch? Susan's got it, tapioca starch. In a pinch I tried rice flower, and it worked okay. Icing sugar also works, but makes the dish sweeter.