If you are using the stock/juices for gravy use cornstarch. Fat gravies use flour (roux). You could also use red wine instead of some of the added water. But if you want to use flour, make sure you mix the flour into some of the hot liquid to make a paste and then mix the thickened flour into the other juices. Cornstarch is used for water gravies. Cornstarch can dull flavor if too much is used so be sure that you taste the gravy and add salt/pepper/spices to bring up the flavor. Bring the liquid to a boil before you add the cornstarch or flour paste. You could also add just a few pats of butter instead of either cornstarch or flour.

This was originally a recipe my mom had submitted for a company cookbook. I suppose you could use cornstarch, however, this recipe calls for dredging the meat in flour and browning it. After years of making this recipe, I add extra fat (a little butter and oil) to the drippings and vegetables and sprinkle them with flour allowing it to brown nicely before adding the water and meat back in. I rarely even have to thicken the gravy, but will add water, as needed, if not using a crockpot. Using red wine would be fine, but will totally alter the flavor, losing the beauty of this recipe... it's beef at its simple finest.