Large handful of flat-leaf parsley, roughly chopped
Dry-fry the chorizo in a large pot over a medium heat until the cubes are crisp. Remove the chorizo from the pot with a slotted spoon, place on a plate and set aside.
You should be left with plenty of the fat and oils rendered from the chorizo while they cooked, but if not, add a drop of rapeseed oil.
Add the onion, fennel and celery and sweat for about 10 minutes until the vegetables have softened.
Add the tomatoes, tomato paste, bay leaf, garlic, chilli and white wine and cook for about 15 minutes over a medium heat until the sauce has reduced slightly.
Pour in the fish stock and stir in the potatoes. Simmer for about 15 minutes until the potatoes are just cooked and then season with sea salt and ground black pepper to taste.
Add the mussels and cook for 3 minutes until they have opened, then add the prawns and cook for a further 2–3 minutes until all the seafood is cooked through. Discard any mussels which haven't opened during cooking.
Serve straight away in deep, warmed bowls with a scattering of chopped parsley. Make sure you serve some crusty bread to mop up the juices.