1) Finely grate enough zest from the orange to measure 1/2 tablespoon.

2) Cut peel, including all white pith, from the orange with a paring knife. Then cut segments free from membranes.

3) Cut out and discard core of fennel bulb, then cut bulbs crosswise into very thin slices, as thin as you can get them.

4) Whisk together vinegar, zest, salt, and pepper in a small bowl until salt is dissolved, then add olive oil slowly in a stream, whisking until combined well.

5) Toast hazelnuts on medium heat on a dry skillet.

6) Toss fennel and oranges with vinaigrette in a large bowl until combined well.

7) Top with toasted hazelnuts and dried cranberries.

8) Garnish with a few fennel fronds.