Heat half the olive oil in a skillet over a medium high heat and add the beans. Cook until browned and crispy. Lower the heat and add the onion, chilli and garlic. Cook for another 5 minutes and season to taste.
Add the tomatoes and the rest of the oil and cook until the tomatoes burst. Add a little water if needed plus more seasoning and bring to a simmer. Use a wooden spoon to squash about a third of the beans so that they help thicken the sauce. Add the fish pieces and cook then add the vinegar.
Serve topped with parsley, olives, sliced chilli and more olive oil plus some crusty bread.
Nutrition information is an estimate and will vary depending on the exact ingredients used.