In a stockpot, warm the stock over low heat. Peel the prawns (keeping the tails on), throwing the heads and shells into the stock pan as you go. De-vein the prawns by running the tip of a knife down the backs of the prawns. Then score a little deeper so they butterfly as they cook.
Now, in a large casserole dish add sliced the sausages and on a medium-high heat with 1 tablespoon of olive oil, cook for 10 mins, or until they have released their tasty fat.Once done, remove the sausages to a plate but leave the fat in the pan to make the roux with.
The roux
On low heat, stir the butter and flour into the pan, scraping up all the brown bits from the bottom of the casserole dish from the sausages.Now, it's time to be patient. Keep stirring for 25 - 40 mins, or until dark golden brown. The darker the tastier. You want the roux to have a semi-loose, doughy consistency.
Cajun holy trinity
Deseed the peppers, peel the onion and roughly chop with the celery, and stir (this holy trinity) into the roux pan. Scrunch and add the bay leaves and strip in the thyme leaves, then peel, finely chop and add the garlic, followed by the cayenne and Tabasco.Put the sausage back into the pan, add the tomatoes, stirring as you go.Strain the stock through a sieve (to catch the shells and heads if you used fresh prawns) then add the stock and let simmer away for 10 mins.Finely chop the parsley.Slice the fish into nice chunks. Sort through the cockles or clams and tap them – if any stay open, throw them away.Now, add all the fish and seafood to the pan and simmer for a few mins, or until perfectly cooked – the prawns should be pink and the clams or cockles open (discard any that remain closed), stirring regularly.Squeeze over lemon juice to taste, and scatter with the chopped parsley.