By the unit
Radicchio is "sometimes known as Italian chicory because of its common use in Italian cuisine. It is grown as a leaf vegetable and usually has colorful white-veined red leaves that form a head. Radicchio has a bitter and spicy taste which mellows if it is grilled or roasted."
Source: https://en.wikipedia.org/wiki/Radicchio
Recipes: https://www.bonappetit.com/ingredient/radicchio