Clean the fish and seafood as required, remove prawn shells, fillet and remove bones from the fish, slice off heads. Reserve. (If your fishmonger does this for you, ask him to reserve the extras.)
In a large saucepan, add all the fish and seafood extras (heads, bones, etc.), along with the celery, carrot, 1 onion, salt and pepper. Cover with water. Bring to the boil, then reduce to a steady simmer and cook for 15 to 20 minutes. Strain the stock and reserve.
In a saucepan, heat the olive oil over medium heat. Add the remaining onion, garlic and chilli and cook gently until softened.
Pour in wine or cognac. Add squid, cut into strips. Cook 5 minutes over medium heat.
Add chopped tomatoes, bring to the boil and add the remaining fish and seafood. (The fish should be in chunks and the clams and mussels in their shells.)
Pour 1 glass of fish stock (about 250ml) in the saucepan. Keep cooking on medium heat for 15 to 20 minutes.
While the soup is cooking, lay a slice or two of toast on the bottom of each bowl. Once ready, top with the fish soup, sprinkle with some parsley and serve!
Your selection of fish and seafood can vary slightly, but for a traditional Mediterranean assortment choose squid, prawns, scorpion fish, anglerfish, clams and mussels.