Place the tomatoes in a food processor and pulse to chop coarsely. Do not purée.

Heat 1/3 cup olive oil in a large frying pan over medium heat. Add the tomatoes, onions, and garlic. Cook, stirring occasionally, until the tomatoes begin to give up their juice and the onions are soft.

Add the oregano or marjoram, salt, and pepper. Reduce the heat and simmer, stirring occasionally, for about 10 minutes or until the mixture thickens slightly.

Remove from the heat and stir in the parsley and capers or black olives. Taste and add salt if needed.

Preheat the oven to 350 degrees Fahrenheit. Coat the bottom of a baking dish with a little olive oil. Place the fish in the dish, skin-side down.

Spoon the tomato sauce over the fish, making sure to cover it completely. Bake for about 20 minutes or until the fish flakes and is done.

Serve with Italian bread for sopping up the sauce, if desired.