• Make-Ahead

Ingredients

1. 1/2 cup hazelnuts
2. 4 tangerines or 2 navel oranges
3. 2 tablespoons sherry vinegar
4. 1 tablespoon white balsamic vinegar
5. 1 1/2 teaspoons honey
6. 1 small shallot, minced
7. 1/4 teaspoon finely chopped thyme
8. 1/4 cup extra-virgin olive oil
9. 2 tablespoons hazelnut oil
10. 1/4 teaspoon truffle oil (optional)
11. Salt and freshly ground pepper
12. 3 large bunches of watercress, thick stems removed
13. 1 3/4 cups loosely packed flat-leaf parsley leaves (from 1/2 bunch)
14. 3/4 pound thinly sliced prosciutto, preferably duck prosciutto

Directions

1. Preheat the oven to 350°. Spread the hazelnuts in a pie plate and toast for about 10 minutes, or until fragrant. Let the nuts cool slightly, then coarsely chop.
2. Meanwhile, peel the tangerines, removing all the bitter white pith; if using oranges, peel with a sharp knife. Working over a large bowl, cut in between the membranes to release the citrus sections.
3. In a bowl, whisk the sherry vinegar with the balsamic vinegar, honey, shallot and thyme. Whisk in the olive oil, hazelnut oil and truffle oil in a slow stream. Season the dressing with salt and pepper.
4. Add the watercress and parsley to the tangerine sections and toss. Add 1/3 cup of the dressing and toss well. Arrange the salad on a large platter; arrange the prosciutto decoratively around the salad. Sprinkle with the toasted hazelnuts and serve with the remaining dressing.

Make Ahead

The recipe can be prepared a day ahead through Step 3. Keep the hazelnuts at room temperature; refrigerate the oranges and dressing separately.