I can use it at the beginning of cooking something (as a roux, as in for bechamel) or at the end to thicken (as buerre marnie, as in for stew), essentially the same way ThatBobbieGirl does.

I found the niftiest ice cube trays with silicone bottoms – the cubes just push right out and into a baggie.

What I prefer to do is to freeze the roux. I save chicken and beef fats to cook with, and some of each gets made into little squares of roux that I can just drop into a pan to thicken up a sauce, gravy or soup. In fact, right now i’m eating a cube steak with a little beefy mushroom gravy. A lot of juices cooked out of the mushrooms and meat, so I decided to just plop a few squares of beef tallow roux into the pan to thicken up the juices into a bit of gravy, to make dinner just a bit nicer.

While I do this all the time with fats saved from cooking, I’ve yet to do it with butter — although it has been on my mental list of things to do for quite a while.

Mochicko is similar to cornstarch, and can be found at most Asian markets and some health food stores.

Here’s a link that tells more about it: http://www.wisegeek.com/what-is-mochiko-flour.htm