Gari as subtitutes for tapioca I used to make a lot of cakes using tapioca flour. Now I've moved to another country and rarely stumbled upon the flour in the supermarket. Last time I found gari which also made from cassava. Can I substitute gari for tapioca? Can I put it in food processor first to make the texture more similar? From what I've read, usually gari's mixed with water to make porridge, but I don't have a lot of ideas in how to use it (other than all my tapioca flour recipes).

Thank you.
Most western substitutes call for using Corn Starch instead since the two have similar binding properties. For example see this:

http://www.buzzle.com/articles/tapioca-flour-substitute.html

Garri/Gari may seem closer to home, since it made from Tapioca as well (aka Casava), but it is a different composition than Tapioca flour. While Tapioca flour is primarily starch, Garri's composition is somewhat the opposite since Garri is what remains after the starchy water is drained from mashed-up, oiled Tapioca.

As suggested, look for starch-based flours, your best option is Corn Starch available in most countries.

Sources for my research:

On Tapioca Starch:
http://www.bobsredmill.com/blog/healthy-living/what-is-it-wednesday-tapioca-flourstarch/

On Garri: Wikipedia :)