Rinse Salted Cod in water for at least 3 times until water comes out clean. As you can see in the top right picture, the water has a lot of salt floating in it. This was the first rinsing. After the 3rd rinse, the water is clear, as shown in the picture at the bottom left. Leave the fish to soak in this water for about 6-8 hours. It will be tender after the soaking time, as you can see in the bottom right picture.
Rinse and drain the fish again and place in a large stock-pot with clean cold water. Gently simmer over a medium-high heat for about 7 minutes until it is tender. Drain fish and set aside, reserving some of the cooking liquid in case your sauce get dry and you need more liquid.
While the fish is cooling, place tomatoes on a hot griddle to roast.
Roasting the tomatoes will take about 10 minutes. If the fish is already cool enough to handle, shred it finely.
Place roasted tomatoes in a blender and process until you have a smooth sauce. Strain using a sieve and set aside.
Heat the olive oil in a large skillet over medium heat. Add the onion and cook until transparent, about 4 minutes, then stir in the garlic and cook for a couple more minutes. Add the roasted tomato puree and cook for about 5-7 minutes.
As soon as the tomato sauce starts simmering, add the shredded Salted Cod. Stir and cook until the tomato sauce starts simmering again, and, one by one, start slowly adding the raisins, olives, and cappers. Allow the sauce to simmer and the flavors to blend. Now, add the potatoes and keep simmering and stirring.
Finally, add the roasted red pepper strips, freshly crumbled Mexican oregano, parsley, and pickled “Guero” peppers. Season with pepper and salt to taste. Remember that the fish was already salted, so be careful not to add salt before tasting the sauce. Keep simmering for about 10-15 more minutes or tomato sauce has reduced.