The Language of Food: Slurry
This is one of my all time favorite cooking words: slurry. It sounds kind of gross, but it means so much to gravy, sauce, and stew. You can thicken anything with a proper slurry, and it's not hard to make.
In Austrailia, Slurry is a slang term for a promiscuous woman. But on this side of the Pacific, slurry is basically a suspension of solid particles in a liquid. Such a bland definition for such a beautiful and powerful culinary tool. Wikipedia has about 13 definitions for slurry, none of which really have anything to do with sauces and gravy. And there's also this very disturbing definition that will make your stomach churn if you have ever eaten anything in nugget form.
Slurry is not on any official culinary list of terms because most professional chefs prefer not to thicken sauces or stews with a slurry. Most pros use a roux or a bechamel sauce as a base to make thick sauces. The problem is that we are not professional chefs, and sometimes our soups, stews, or gravies are thinner than we would like.
So one of the easiest ways to thicken a stew or gravy is to use a slurry. There are a few different ways to make a slurry, but most of them involve corn starch. I use corn starch over flour because it dissolves faster in water and the starches bloom faster under heat then the flour. My ratio of starch to liquid is this: 1 tsp. starch per 1 cup liquid for large amounts like stews or soups. For sauces or gravy, I will reduce the liquid to 1/2 cup per 1 tsp. of starch.
For a savory sauce or stew, whisk corn starch into beef stock or broth. For a creamy sauce, use milk. You can even use water in a pinch, but water just doesn't bring any flavor to the table. After the starch is dissolved, pour as much as you need into the dish. Stir briskly as the dish heats and it will thicken up quickly.