A Note on Thickeners

cornstarch, apparently, is not a very dependable thickener. according to my research, its thickening effect is somewhat fragile, and if used improperly the result can actually be to thin out the soup/sauce/whatever in question. as you may or may not know, in order to activate its thickening power, cornstarch needs to be brought to a boil. however, after it has started to do its work, overstirring can break up the thickened network that the cornstarch has created, releasing excess liquid and actually thinning the substance! boo.
flour is a much less volatile thickener; however, it adds a more noticeable taste to your dish, so i would also recommend using it sparingly. if you do decide to use it, create a roux by mixing it with some sort of fat (butter, grease, even milk can work) and cook it for awhile to get rid of some of that raw flour taste. it’ll change color as it cooks (alton brown does a great special on gravies around thanksgiving time that explains rouxes in detail – keep an eye out for it!) after you’ve cooked it to the desired level, stir it into your sauce/soup. (this is my trick for particularly fussy alfredo sauces – i know it’s cheating, but it works like a charm!)for more on how cornstarch works, see http://www.exploratorium.edu/cooking/icooks/10-06-03.html