A slurry- is a combination of starch (usually cornstarch, flour, potato starch or arrowroot) and cold water which is mixed together and used to thicken a soup or sauce. If the starch is solely added directly to a hot liquid, the starch granules cannot disperse easily and clumps form. Once mixed with water, the slurry can be added directly to the hot liquid. The liquid must be brought up to a simmer each time to ensure the starch reaches it’s full thickening potential before more is added. Add a bit at a time until you reach the desired consistency.