I've never worked much with tapioca flour. We used it a little bit at a Thai restaurant I worked at once but I don't even remember what for. I'll be picking up some soon. They look similar to gougères which are a French pastry made with pâte àchoux. The same dough you would make cream puffs or profiteroles with but with added cheese. Gougères come out mostly hollow and are delicious. They can also be piped full of cheese filling just like you would pipe pastry filling into a cream puff.
