Heat 2 tablespoons olive oil in a heavy saucepan over medium heat. Add the onions and garlic and cook, stirring, until the onions are golden, about 7 minutes. Add the tomatoes and olives and cook, stirring occasionally, until the sauce thickens, about 25 minutes. Add the salt and pepper. Keep warm until ready to serve.
Preheat the oven to 400?F.
Cook the linguiÁa in a large skillet over medium heat, stirring often, for 3 minutes. Add the bread crumbs and mix to bind the sausage.
Season the fish fillets with the Essence. Heat the remaining olive oil in a large ovenproof skillet or two smaller ones over high heat. Add the fish and sear until slightly golden, 1 to 2 minutes on each side. Carefully drain off any excess oil. Put an equal portion of the linguiÁa mixture on each fillet. Bake for 5 minutes.
To serve, arrange the fillets on eight serving plates. Spoon the olive-tomato sauce over each and sprinkle with the feta cheese.
Yield: 8 servings