If you wish to reduce the sodium content of this recipe, drain capers from their brine, and soak them in water for 30 minutes.
Place the whole can of tomatoes, juice included, in a bowl. Crush them slightly with your hands or with kitchen scissors. The result should be chunky but without any large pieces.
Heat 1 tbsp olive oil in a large sauté pan. Add onion, sliced poblano pepper and a pinch of salt. Cook a few minutes until onions are translucent and peppers are soft.
Add garlic, dried oregano and bay leaf and cook another minute or two until fragrant. If using fresh oregano, add it in the next step.
Add tomatoes to the pan, along with capers and olives (and fresh oregano if using). Season with some fresh ground pepper.
Bring to a boil, reduce heat, cover and simmer for 15 to 20 minutes, stirring occasionally.
While the sauce is cooking, heat a large skillet over medium high heat.
Season fish on both sides with salt and pepper.
Drizzle the remaining tablespoon of olive oil into the pan. Add the fish. Cook for 3 minutes on both sides, or until the fish turns opaque and is thoroughly cooked. Please note that the cooking time may differ based on the thickness of the fish cut.
Serve the fish topped with a quarter of the sauce. Sprinkle some minced parsley for garnish.