Sloppy Joes are a traditional American dish, made from ground beef, onions and a sweet sauce. There are several sloppy Joe recipes available in cookbooks and on the Internet to choose from. However, if the recipe you chose uses too much water or other liquid in the sauce, the result will be more of a ground-beef stew than a thick sandwich filling. You can thicken sloppy Joes with simple ingredients and have the meal ready in approximately 30 minutes.
Combine cornstarch and warm water in a small bowl for every 3 cups of sloppy Joe mixture you need to thicken.
Stir the cornstarch and water mixture with a spoon. Press the back of the spoon against the walls of the bowl to break up any clumps of cornstarch that form. Continue stirring until the mixture is completely smooth. If you allow the mixture to clump up, the sloppy Joes will not thicken, and will develop small, chewy dumplings in the sauce.
Pour the cornstarch and water into the sloppy Joes mixture and stir with a spoon until thoroughly combined.
Cover the sloppy Joe mixture and simmer for 30 minutes, stirring occasionally. If the mixture is still too thin for your preference, make a second batch of cornstarch and water mixture and repeat.