If you don’t have the time, weather, or inclination to start a fire, it’s easy to grill radicchio on a cast iron grill pan.
2 heads radicchio, round or elongated (Treviso)
Rinse off the radicchio and discard any damaged portions. Cut round radicchio in quarters, and elongated radicchio in lengthwise halves. Drizzle with olive oil and season with salt.
Preheat a cast iron grill pan until it is very hot (if you’re grilling over fire, you need moderately hot coals), and grill the radicchio on all sides until the outer leaves are nicely browned. Remove from the grill.
Serve immediately drizzled with a little best quality balsamic vinegar. For use in another recipe, cut out any tough center core, and roughly slice or chop into pieces.