A lot of the baking recipes I've stumbled across have arrowroot as one of the ingredients. I know it looks like flour, but what in the world IS arrowroot, anyway?
According to wikipedia,
Arrowroot can be used as a thickener for acidic foods, such as Asian sweet and sour sauce. It is invaluable in cooking when you wish to have a clear, thickened sauce, for example, a fruit sauce. It will not make the sauce go cloudy, as for example will cornstarch, flour or other starchy thickening agents.
The lack of gluten in arrowroot flour makes it useful as a replacement for wheat flour in baking. Like other pure starches, however, arrowroot is almost pure carbohydrate and devoid of protein, thus it does not equal wheat flour nutritionally.
Arrowroot thickens at a lower temperature than does flour or cornstarch, is not weakened by acidic ingredients, has a more neutral taste, and is not affected by freezing. It doesn't mix well with dairy, forming a slimy mixture. It is recommended to mix arrowroot with a cool liquid before adding to a hot fluid. The mixture should be heated only until the mixture thickens and removed immediately to prevent the mixture from thinning. Overheating tends to break down arrowroot's thickening property. Substitute two teaspoons of arrowroot for one tablespoon of cornstarch, or one teaspoon of arrowroot for one tablespoon of wheat flour.