Radicchio is a type of chicory green that thrives in cooler temperatures and is tremendously popular in Europe, where it's prized for its crispness and robust bitter flavor, as well as its astonishingly beautiful leaves.
Radicchio keeps quite well in an open plastic bag, in the refrigerator, for two weeks or more.
Radicchio stands up to bold, rich ingredients like toasted nuts, garlic, capers, fresh croutons, anchovies (even if you think you don’t like them), and strong cheeses (think blue cheese, parmesan, fontina, or goat cheese). Radicchio leaves are at their brightest when eaten raw: torn or chopped and tossed in a salad. They also do well cooked: grilled or roasted in wedges, or wilted in a soup, risotto, or pot of beans. If serving in a salad, be sure to give it a stronger-than-usual dressing, maybe with sherry vinegar, red wine vinegar, and/or lemon juice.