Desalt the Bacalao: Start by desalting the salted codfish. Rinse the bacalao under cold water to remove excess salt. Then, place it in a large bowl of water and let it soak for at least 4 hours, changing the water every hour. For best results, soak overnight in the refrigerator.
Boil the Bacalao: After soaking, drain the water and place the bacalao in a pot with fresh water. Bring it to a boil and cook for about 10 minutes. Drain and let it cool slightly. Once cooled, flake the bacalao into bite-sized pieces, removing any bones or skin.
Cook the Bacalao: In a large skillet, heat the olive oil over medium heat. Add the sliced onions, bell peppers, and garlic. Sauté until the onions are translucent and the peppers have softened.
Add Flavors: Stir in the tomato sauce, vinegar, capers, and olives. Cook for another 5 minutes, allowing the flavors to meld together.
Combine and Simmer: Add the flaked bacalao to the skillet, stirring gently to combine. Reduce the heat to low and let it simmer for about 10 minutes, stirring occasionally. Taste and adjust seasoning as needed.
Garnish: Sprinkle chopped cilantro on top for a fresh burst of flavor.