Drain the meat after browning and sauteing any onions or other vegetables. Sprinkle in 2 tablespoons of flour for every 1 pound of meat, set the burner to low heat and stir the flour until all the meat and vegetables are coated. The bits of fat left in the pan after draining will cling to the flour and eliminate any floury taste.

Add the wet ingredients, such as water, Worcestershire sauce and tomato sauce or ketchup, as well as any spices. Stir well to combine.

Turn the heat to low and allow the mixture to simmer, stirring occasionally to prevent sticking. The filling will begin to thicken within five to 10 minutes. Sloppy Joe filling thickened with flour can be frozen and re-heated again later, though some loss of thickening may occur.

Pour 1 tablespoon cold water into a jar that has a tight-fitting lid. Add to that 1 tablespoon cornstarch. If your sloppy Joe recipe calls for water, subtract the 1 tablespoon of water from what you add, and use the rest when cooking your filling. Use 1 tablespoon of cornstarch -- and 1 tablespoon of water if not already called for in the recipe -- for every 1 pound of meat.

Screw the lid tightly over the jar and shake it vigorously. Make sure there is no residual cornstarch sticking to the sides of the jar. If there is and shaking doesn’t take care of it, open the jar and stir it with a clean fork, scraping along the sides until you can no longer see the white powder. Cover the jar and shake it again until all the lumps are broken and mixture is smooth.

Add the cornstarch mixture after the filling has cooked, pouring out a slow, steady stream with one hand and stirring the sloppy Joe mixture with the other. Stir well to combine, and allow the filling to simmer for one minute, stirring to avoid sticking, until the mixture has thickened. Remove the pan from heat immediately after the mixture has thickened.