Preheat the oven to 400 degrees F.
In a mixing bowl, toss the potatoes with 3 tablespoons of the olive oil and season with salt and pepper. Transfer to a shallow roasting pan or baking sheet and bake until golden brown and crisp around the edges, stirring occasionally, 30 to 40 minutes. Remove from the oven and set aside.
In a large skillet heat 3 tablespoons of the olive oil and, when hot, add the shallots and garlic and cook until soft, 1 to 2 minutes. Add the potatoes and toss to combine. Add the onions and fennel and cook, stirring occasionally, until just warmed through but still crisp-tender, about 5 minutes. Season with salt and pepper, to taste, and set aside to keep warm while you prepare the fish.
Season the fish well on both sides with salt and pepper and lightly brush with olive oil. Heat a large skillet until very hot and add the remaining 2 tablespoons of the oil. Add the fish fillets, skin side down, and cook until golden brown and crispy around the edges. Turn the fillets so that they are skin side down and transfer to the oven. Bake until just cooked through. (This will depend on the type of fish you choose to use.) Remove from the oven and set aside briefly.
Divide the vegetable mixture evenly among 6 plates, and serve the fish fillets over the top of the vegetables. Garnish the plates with the orange segments and then drizzle some of the Kalamata Gremolata Sauce over the fish fillets and vegetables and serve immediately.
In a bowl combine all ingredients and stir to blend. Serve the sauce spooned over fish.
Yield: 1 1/2 cups sauce