Slurry

A slurry is a simple and quick thickener: a mixture of starch (corn, potato) or flour stirred into a small amount of cold liquid until it forms a smooth, lump-free suspension.

The main rule is that the starch is dispersed precisely in cold water or broth, and only then poured in a thin stream into the hot dish with constant stirring. If dry starch is added straight into something hot, it instantly seizes into lumps. After the slurry is added, the dish is brought to a boil, and the starch, swelling, gives it the required thickness and a pleasant sheen. Unlike a roux, a slurry adds no flavour and barely changes the colour, so it is ideal when one only needs to thicken a liquid — from Asian sauces to fruit kysils and gravies. It is one of the basic techniques in every cook's arsenal.