Preheat the oven to 350 degrees F. Spread the hazelnuts out on a baking sheet and toast until golden, 8 to 10 minutes.
Cool and slightly crush (the bottom of a measuring cup works well).
Add the coriander to a small skillet and swirl over medium heat until toasted, about 2 minutes.
Crack the coriander and add to a baking dish along with the hazelnuts, shallots, vinegar, honey, 1/2 teaspoon salt, the cayenne and the juice of 1 orange.
Whisk in the olive oil in a slow and steady stream.
Set aside.
Fit a medium, shallow pot with a steamer insert and add about an inch of water.
Bring to a simmer, add the carrots, cover and steam until just fork-tender, 10 to 12 minutes.
Transfer to the baking dish, toss gently and allow the carrots to cool in the vinaigrette at room temperature.
Segment the remaining orange and arrange the carrots on a serving platter, topped with the orange segments.