Soak the codfish overnight in water, changing the water 2 times.
In a medium pot, with enough water to cover the salted codfish, cook for about 15 minutes. Strain and remove any bones. Set aside.
In a large sauce pan warm the oil. Add the onion, scallions, red bell pepper, tomato and garlic. Cook until all the vegetables are soft. Season with salt and pepper. Add the fish, stir well and cook for about 5 minutes more.
Serve warm with arepa on the side.