Cut cod into serving-size portions. Pat dry. Dredge lightly in flour. In large skillet, heat half of the oil over medium-high heat; brown cod lightly on both sides and arrange in 8-inch (2 L) square baking dish. Sprinkle with feta.
Pour remaining oil into skillet; cook onion, garlic and green pepper, stirring, until softened, about 4 minutes. Add tomatoes; crush with fork and stir in olives, oregano, pepper flakes and sugar. Bring to boil, reduce heat to medium-low and simmer, stirring often, until thickened, about 10 minutes.
Add parsley, and season with salt and pepper to taste; spoon over fish. (Dish can be made ahead, cooled, covered and refrigerated for up to 8 hours. Add 5 minutes to baking time.) Bake uncovered in 375°F (190°C) oven for about 15 minutes or until bubbly.