For crisping, rice flour. (Potato may also work but I'm less certain)

LALA, thanks for the link. It's about thickening, however.

Thnaks, Gooster, but I don't have any rice flour! And I don't think my spice grinder will get rice fine enough. I'll give it a try. I do have some very dry rice. :)

Try arrowroot - it seems the closest.

Is it tapioca flour? Because that might be OK as well.

how about ... bleh ... ground grits?

it's good for crunchy pork chops ...

or panko?

I use both potato starch and tapioca starch for thickening. Potato starch will not maintain its thickening properties in a sauce when it is reheated, however - it is more of a one-time shot, for which it works very well.

If you have tapioca and arrowroot, I would use one of those for the cookies.

I use potato starch as a substitute for taro root when I make okonomiyaki.

Thanks, everybody! Even Dave--the grits idea was relevant, but although cornstarch is often called corn flour, it's not just ground up corn. It's boiled and separated and washed to get the starch out.

Yes, it's powder tapioca starch. I also have tapioca pearls, but that's different. You have to soak pearls to reduce them back to starch, but then it's too wet to use as starch.

I checked two stores for cornstarch and neither had a box. One had one small tin. The other had four slightly larger, but definitely gravy thickening size (I use Wondra for that). I will get a gravy sized Clabber Girl non-gmo tin (plastic?) for things like cookies. I don't really need a whole box right now--just usually have one.

If this happens again, I'll go for the arrowroot.

The dearth got me to decide that substituting on a recipe I haven't made before is just silly. So I made up a cookie to use what I'd already measured out. It's pretty good. I'll start another thread.

If you have an egg drop soup packet hanging out ... you could use that in a pinch ...

I buy Clear Jel instead of regular cornstarch, but it is not as good in soups as regular cornstarch or tapioca starch.