I have a lovely recipe (for stir-fried tofu) that uses arrowroot as its thickener. This is easy to use, and adds a nice subtle flavour of its own to the dish. However, I am now living somewhere where I can't find any - what would you recommend as an alternative? The flavours of the dish are quite delicate, and it is fried at a quite high heat.
Corn starch (aka cornflour) will usually work and is more readily available, but it won't work well for acidic sauces, where you'll want to use tapioca starch. (aka. cassava flour; if all you can find is tapioca in granule form, grind it up first).
For a more thorough list of starch based thickeners and their alternatives, see Cook's Thesaurus: Thickeners
you should be able to use potato starch (or corn starch) as an alternative thickener. Although these will cause the sauce to become cloudy, rather than the clear of arrowroot.