Hahaha, @Giu_DiB , I can believe you 
Before the two weeks of water treatment Radicchio Tardivo is EXTREMELY bitter. During the process, the white crunchy stem grow, and most of the bitter go away. It became sweet and agreeable. That’s why I love to eat Radicchio raw, with orange, salt, olive oil and balsamic vinegar.
When we buy radicchio, we put it inside fresh water. In this way the plant remains fresh, you can eat it even after a week or more
Since radicchio can be eaten both raw and cooked, its use in the kitchen depends only on the cook’s imagination. For example, I like to add a little raw radicchio at the end of the preparation of the radicchio risotto, in order to preserve the “crunchy” effect