Cornstarch (Best Option)
1 tablespoon cornstarch per 1 tablespoon arrowroot powderCornstarch is a common thickening agent derived from corn and works by gelatinizing starch granules when heated with liquid, creating a smooth, glossy texture. It thickens at a similar temperature range as arrowroot, making it ideal for soups.
To use cornstarch effectively, mix it with a small amount of cold water to form a slurry before adding it to hot soup to avoid clumping. Avoid prolonged boiling after adding cornstarch as it can break down and thin the soup.
Compared to arrowroot, cornstarch produces a slightly less delicate texture but maintains clarity and glossiness, making it a very close substitute in soups.