Place a cast iron pan over a medium-high heat. Add the chorizo and cook for 2 to 3 minutes, or until the chorizo releases its oils and begins to turn crisp. Add the onion to the pan and sweat for 5-6 minutes, then add the garlic and cook for another 2 minutes.
Add the chilli flakes, paprika and rosemary, adding a splash of water if the mixture starts to stick.Turn the heat up to high, then add the wine and let it bubble until the volume of the liquid has reduced by half.
Add the chopped tomatoes and turn down the heat to bring it to a gentle simmer and cook for 10-12 minutes, or until the liquid has thickened.
Add the chickpeas to the pan and cook for 5-6 minutes.
Season the ling and place into the pan, allowing the fish to sink into the sauce. Cover and leave the fish to cook gently for 8-10 minutes.
Remove from the heat and season to taste.
Ladle into warmed bowls, grate over a little lemon zest and sprinkle with parsley before serving.