Radicchio appears to be native to Italy, and the three types are named after the towns of their origin: Chioggia, Treviso and Castelfranco, all in the Veneto region. Chioggia is the most common radicchio found here, available pretty well throughout the year. It grows in a tight ball, resembling a small red cabbage and should feel weighty for its size. It has an agreeable bitterness and is excellent in salads on its own, mixed with other leaves, or with fennel. Treviso has long tapering red leaves with meaty white ribs, resembling a white witloof in appearance. It’s milder in flavour and is excellent grilled, baked or roasted and in risotto (I used the Chioggia variety for the recipe above, as Treviso is not readily available, and found it quite successful). Castelfranco is more open, like a young butterhead lettuce, creamy in colour, tinged with pink and speckled with purpley-red. It’s used in salads. The latter two are seasonal, appearing in late autumn.
Here’s one of my favourite salads with radicchio. Capers, garlic and parmesan cheese make a gutsy dressing that stands up well against the bitterness of radicchio. Just be warned; it’s very moreish!