cornstarch mixed with 6 tablespoons water (optional

Cornstarch is a fine, white, odorless powder derived from the endosperm of corn (maize) kernels through wet milling and extraction processes. The production involves separating the starch granules from the protein, fiber, and germ components of the grain. Chemically composed almost entirely of amylose and amylopectin polysaccharides, cornstarch is nearly pure carbohydrate with minimal flavor of its own. When mixed with water, it forms a suspension known as a slurry or beurre manié variant, which has distinct thickening properties as the starch granules swell and gelatinize under heat.

When cornstarch is combined with water in the ratio suggested (approximately 1 part cornstarch to 6 parts water by volume), it creates a thin, pourable mixture commonly referred to as a cornstarch slurry or starch slurry. This mixture is colloidal in nature—the starch granules remain suspended in the liquid until exposed to heat, at which point they absorb water and swell, causing the mixture to thicken significantly.

Cornstarch slurry functions primarily as a thickening agent in sauce-making, gravies, soups, and Asian cooking, where it is valued for producing clear, glossy results without the cloudiness that flour creates. In stir-fry cookery, particularly in Chinese cuisine, cornstarch slurry is tossed with proteins and vegetables before cooking to create silky coatings and sauces. It is also used as a binder in custards, puddings, and pie fillings, and as a finishing slurry to adjust consistency in braised dishes and curries. The mixture must be stirred into hot liquid while continuously stirring to prevent lumping; once incorporated, it reaches maximum thickening power at approximately 190°F (88°C).