Radicchio (pronounced ra-DEEK-ee-o) is a leafy member of the chicory family, often called Italian chicory, which explains its bold, bitter flavor. Although it's compact like red cabbage, radicchio's leaves are thinner and more tender unlike red cabbage's firm and waxy texture.

Radicchio owes its characteristically bitter edge to naturally occurring chemical compounds released when the vegetable is cut or chewed. However, because these bitter compounds are water soluble, you can tone down the bitterness by soaking the cut leaves in water. It takes at least 30 minutes to tame the vegetable’s bite. To tone it down even more, cut the radicchio into fine shreds before soaking, as the greater amount of exposed surface area allows more of the bitter compounds to leach out.

That said, radicchio’s bitterness helps balance flavors, particularly in salads that contain rich ingredients, such as cheese or nuts, or sweet components like fruit.