Step 1Cut the filets into 3-inch pieces, sprinkle them with salt and let them stand 30 minutes.
Step 2Soak the bread in water to cover until it is softened. Squeeze it out and put it in a blender with the garlic, pimenton, oregano and broth. Blend until smooth.
Step 3Heat the oil in a skillet or heat-proof cazuela over medium heat. Pat the fish dry with a paper towel and fry the pieces of fish about 1 minute on each side; the fish does not need to brown.
Step 4Add the blended pimenton sauce and cook until the fish is about halfway cooked, about 10 minutes. If the sauce thickens too much, add additional broth or water.
Step 5Add the cooked potatoes; continue cooking until the fish just flakes easily, about 5 more minutes. Add the vinegar and cook 2 minutes more. Sprinkle with the chopped parsley and serve.