1Heat 2 tablespoons of the olive oil in a saucepan over medium heat. Add the onions and garlic, and cook while stirring, until the onions are golden, approx 7 minutes. Add the tomatoes and olives and cook, while stirring, until the sauce thickens, approx 25 minutes. Add the salt and pepper. Keep warm until it's ready to serve.
2Preheat the oven to 400 degrees F.
Cook the linguica in a large skillet over medium heat, while stirring, for about 3 mintues. Add the bread crumbs and mix to bind sausage.
3Season the fish with the Essence. Heat the remaining olive oil in a large ovenproof skillet, over high heat. Add the fish and sear until they are slightly golden, approx. 1-2 minutes on each side. Carefully drain off any excess oil. Put an equal portion of the linguica mixture on top of each fish fillet. Bake for about 5 minutes.
4Arrange the fillets onto 8 serving plates. Spoon the suace over each.