Segment 2 naval oranges and set aside. Juice the remaining pith into a large bowl (you should have about 1/4 cup juice). In the same bowl grate 1 small shallot and 1 large garlic clove. Cover with 1 tbsp sherry vinegar, 1/2 tbsp grainy mustard, 1 tbsp honey, 1 tsp fennel seeds and 1/4 cup olive oil. Mix until emulsified, taste and adjust seasoning. Set aside.
Heat a seasoned cast iron on medium-high heat. Cut 2 heads of radicchio into quarters and drizzle with olive oil and a pinch of salt, then massage with your hands. When the pan starts to smoke, add your radicchio and sear on each side for 2-3 minutes, or until deeply charred. Remove and set aside to cool.
Using a mandoline, thinly slice 1 fennel bulb and roughly chop 1/2 cup blanched hazelnuts. Set aside. By now the radicchio should be cooled. Cut the root off each wedge and transfer the leaves to the bowl with the dressing. Add the sliced fennel, season generously with salt, then give it a toss. Taste and adjust seasoning.
Transfer to a shallow bowl, or serving platter, and cover with chopped hazelnuts and orange pieces. Top with shaved aged goat cheese and enjoy!
