How to Make It
In a large bowl, combine the radicchio leaves with 3 tablespoons of the olive oil, the fish sauce and lemon juice; toss to coat the leaves.
In a large skillet, heat the remaining 2 tablespoons of olive oil until shimmering. Add the radicchio and cook over moderately high heat, stirring, until it is golden in spots and just wilted, about 2 minutes. Stir in the white balsamic vinegar.
Transfer the radicchio to plates and top with the cheese. Drizzle with the vin cotto and serve with lemon wedges.
Castelfranco is a mild member of the radicchio family. It has pale yellow or green leaves with red speckles.