Definition:

A white, powdery thickening agent that comes from corn. Products thickened with cornstarch have a clearer, more translucent appearance than mixtures thickened with flour, which produces a more opaque look.

Storage

Cornstarch will keep up to 2 years in a cool, dry place.

Substitutions

Use 1 tablespoon arrowroot in place of 1 tablespoon of cornstarch.
Use 2 tablespoons flour in place of 1 tablespoon of cornstarch.

Q\A:

Q: How do you cook with cornstarch and not get lumps?

A: To prevent lumps when cooking with cornstarch, combine equal parts cornstarch and cold liquid. Add this to the hot mixture you wish to thicken and stir constantly until the mixture boils. Cook and stir for 2 minutes after boiling.
Stirring frequently during thickening also helps prevent lumps.