You can buy potato starch at your grocery store sold as potato flour or starch flour, or if you're feeling adventurous, you can make your own. Potato starch is often used as a thickener for many sauces, soups and gravies. Compared to cornstarch, potato starch can handle higher temperatures. Potato starch also adds moisture when baking. It is made using an involved process of washing, grating and then squeezing the starch from the potato shavings. It can be made into a powdered or liquid form.
Make Your Own Potato Starch
Start by grating some raw potatoes very finely. Place the grated pieces in a layer or two of cheese cloth and squeeze any liquid from the potatoes into a bowl. Next add some water and squeeze the pulp again until the water runs clear. Place the liquid in the refrigerator for about four hours to let the pulp settle on the bottom of the bowl. Carefully remove the container from the refrigerator and slowly pour off the layer of water that is now on top into another bowl or container. Add some more water and stir the starch. Place back into the refrigerator for about an hour to allow the starch to settle again. After an hour remove the bowl from the refrigerator and pour off the excess water again. Whatever is left in the first bowl is the potato starch. You can now allow the remaining liquid to dry and become a powder.
Use It as a Thickener
You can substitute potato starch for cornstarch or white flour as a thickener. It works better to dissolve the potato starch in a small amount of water first to help it mix easier when added to a sauce or gravy. A lot of people favor potato starch over flour because it keeps a translucent texture instead of clouding up sauces and gravies like flour does.
Potato starch is gluten free, which is great news for people who need to stay on a gluten free diet. You can still enjoy the great tastes of gravies and sauces without using wheat flour as a thickener.
It's probably a good idea to check the label on commercially prepared potato starch. Sometimes they could contain wheat flour, especially if the package doesn't say "gluten free."