Thickening with cornstarch slurry
Cornstarch is made of tiny granules that swell and burst when heated in liquid, thickening it into a clear, glossy gel. Stir the powder into cold water first. Dropped dry into hot liquid, each clump gels on the outside and traps dry powder inside.
Stir it again, add it last
Starch sinks to the bottom of the cup within moments, so stir the slurry right before it goes in. Pour it into a simmering sauce near the end, stirring, and let it bubble gently until it turns clear and thickens. Long boiling can thin it out again.
Test yourself
Questions from the interactive lesson, with the answer and the why.
Why mix cornstarch with cold water before adding it to a pot?
To spread the granules out so they don't clump. Separated granules swell evenly when they hit the hot liquid.
True or false: A cornstarch slurry thickens a cold sauce on its own, before any heat is applied.
False. Starch granules swell and thicken only once the liquid is hot, near a simmer.
What went wrong? You sprinkle dry cornstarch straight onto a hot sauce. White lumps form and never dissolve.
The starch needed a cold-water slurry first. Dry granules clump in hot liquid, and a slurry separates them.
Fill the blank: Cornstarch sauces look glossy and clear, while flour-thickened sauces look ___.
Cornstarch sauces look glossy and clear, while flour-thickened sauces look cloudy. Flour contains proteins and other bits that make the sauce opaque.
You pour slurry into a sauce and nothing happens at first. What do you do?
Keep stirring over a gentle simmer a little longer. The granules need a moment of heat to swell and thicken.
