Persimmons are a sweet, succulent foil to the bitter greens in this winter salad that makes a striking holiday side. If you can't find them, firm ripe pears are a delicious alternative.
Pulse shallot in a food processor until finely minced. Add oil, vinegar, mustard, salt and pepper; process until emulsified. Add hazelnuts and pulse until finely chopped.
Combine escarole, radicchio and persimmons in a large bowl. Drizzle the dressing over the salad and toss to coat. Sprinkle with Manchego.
To make ahead: Refrigerate vinaigrette (Step 1) for up to 2 days. Bring to room temperature before serving.