4 Treviso radicchio heads
Extra-virgin olive oil for drizzling, plus 8 tbsp
Sea salt and freshly ground black pepper, for seasoning to taste
2 cloves garlic, smashed
2 tbsp capers
1 tsp prepared horseradish
2 oil-packed anchovy fillets, preferably italian
Leaves from 1 bunch fresh flat-leaf parsley
Leaves from ½ bunch fresh mint
Remove and discard any blemished or discolored leaves from the radicchio heads, then cut each head into quarters. Arrange the quarters on a baking sheet, drizzle them lightly with olive oil, sprinkle lightly and salt and pepper, and toss to coat. Set aside.
Finely grate the zest from the lemon, then halve the fruit and squeeze the juice from one half into a small bowl. Set aside the remaining half.
In a bowl of food processor, combine the lemon zest, garlic, horseradish, capers, and anchovies. Process until will chopped. Add the parsley and mint leaves, lemon juice, and 2 tbsp of the olive oil. Pulse until the mixture forms a coarse puree. With the motor running, slowing pour in the remaining 6 tbsp of olive oil and process until smooth; it should have the consistency of pesto. Transfer the mixture to a bowl and taste and adjust the seasonings. If desired, add a bit more more lemon juice.
Heat a ridged grill pan on the stovetop over medium heat. When it is hot, add the radicchio quarters in a single layer and cook until they just begin to wilt and caramelize, 2 to 3 minutes per side. Transfer to a serving plate and drizzle with the salsa verde. Serve hot or at room temperature. Serves 4.