A fruity Provençal olive oil is ideal for this dressing. Its mild flavor doesn't compete with the taste of the truffle.
For the Dressing
- 1 egg (in shell)
- 1 medium fresh black truffle, cleaned
- 2 tsp. fresh lemon juice
- 1⁄4 tsp. dijon mustard
- 1⁄4 tsp. salt
- 1⁄2 cup mild extra-virgin olive oil
For the Salad
- 1 (3–4-lb.) chicken, cut into 6 pieces
- 2 carrots, peeled and trimmed
- 2 ribs celery, trimmed
- 1 white onion, peeled and halved
- 1 bouquet garni (4 sprigs parsley, 2 sprigs thyme, and 1 bay leaf, tied with kitchen twine)
- 5 heads belgian endive, trimmed and coarsely chopped
- 1 head curly endive (frisée), leaves separated and torn into bite-size pieces
- Freshly ground black pepper
For the dressing: Put egg and truffle into a small bowl, cover with plastic wrap, and refrigerate for at least 24 hours to let truffle perfume egg. Remove egg and truffle from bowl and set truffle aside. Crack and separate egg, discarding white and putting yolk into a medium bowl. Whisk yolk until thick, 15–30 seconds. Whisk in lemon juice, mustard, and salt. Add oil in a slow, steady stream, whisking constantly. Set aside.
For the salad: Put chicken, carrots, celery, onions, bouquet garni, and salt to taste into a large pot. Add enough water to cover, and bring to a boil over high heat, skimming any foam as it appears. Reduce heat to medium-low and poach, partially covered, until chicken is cooked through, 30–45 minutes. Transfer chicken to a plate and set aside to cool. (Strain stock and reserve for another use.) Pull chicken meat from bones and remove skin; discard bones and skin. Cut chicken into pieces and transfer to a salad bowl.
Grate reserved truffle on large holes of a box grater onto a plate. Add belgian endive, curly endive, dressing, half the truffles, and salt and pepper to taste to bowl; toss well. Serve garnished with remaining truffles.