Rinse the fish and pat dry. Slice the tangerines thinly; remove and reserve the fronds from the fennel bulbs and cut the bulbs into thick slices. Mix them together in a bowl with 1/4 cup olive oil and salt and pepper, to taste. Season the fish inside and out with salt and pepper. Stuff the fish with the tangerine mixture and tie it closed with kitchen string. Heat an ovenproof saute pan over medium high heat and add 1/4 cup olive oil. When hot toss in the fennel seeds and peppercorns. Cook to flavor the oil for about 1 minute, remove the spices and discard them. Place the fish in the pan and cook on each side for about 2 minutes. Put the pan in the oven and roast the fish for about 15 to 20 minutes or until cooked through. Serve with the Fennel and Olive Salsa Verde.
Place the fennel fronds, parsley, olives, capers, and anchovies on a cutting board. Chop them with a knife until they are very fine. Put them into a bowl and stir in the olive oil, tangerine juice, and vinegar. Taste the salsa and season with salt and pepper.