Toast the fennel seeds lightly in a small skillet over medium heat for about 2 minutes. Transfer to a cutting board and let the seeds cool. Chop them coarsely.
Combine the orange juice, lemon juice, shallot, orange zest, and garlic in a small bowl. Let sit for 20 minutes and then stir in the fennel seeds and Dijon mustard. Whisk in the olive oil and hazelnut oil and season to taste with salt and pepper.
Cut off the top and bottom of the fennel bulb. Cut it in half lengthwise. Lay one half flat on its cut surface and slice crosswise as thinly as possible. Stop slicing when you hit the core (a little core is all right, but you don't want wide areas of core in your slices). Repeat with the second half. You should have about 1-1/2 cups sliced fennel.
Put the sliced fennel in a large bowl with the arugula and toasted hazelnuts. Toss with enough of the dressing to lightly coat the leaves (you may not need all of the dressing). Season with salt and pepper to taste and serve.
nutrition information (per serving):
based on four servings;
Photo: Scott Phillips