Is radicchio tardivo much different than ordinary radicchio (comes in a round head, not elongated as in your picture)? Don’t know if radicchio tardivo is readily available.
Peter, also in Berlin it is not quite easy to get Radicchio Tardivo. I think it works also with the round one. Fair to say that the tardivo version has much more flavor. Also it works well as an ingredient for tomatoe sauce. In addition I have seen recipes to roast the whole tardivo in the ofen.