• 1.8 kg (4 lb) heads and bones of white fish such as snapper or whiting
• 800 g (1 lb 12 oz) raw prawns (shrimp), peeled and deveined, leaving the tails intact and reserving the heads and shells
• 230 ml (7¾ fl oz) extra virgin olive oil, plus extra, to drizzle
• 1 garlic bulb, halved, plus 5 garlic cloves, thinly sliced
• 4 bay leaves
• a handful of parsley, stalks reserved and leaves roughly chopped
• 10 black peppercorns
• 4 tomatoes, roughly chopped
• 1 brown onion, finely sliced
• 3 carrots, diced
• 2 leeks, white part only, finely sliced
• 250 ml (9 fl oz/1 cup) white wine
• 125 ml (4 fl oz/½ cup) brandy
• 2 × 400 g (14 oz) tins chopped tomatoes, puréed
• 400 g (14 oz) fillet of skinless wahou or blue-eye trevalla, cut into large chunks
• 500 g (1 lb 2 oz) clams, rinsed

Preheat the oven to 180°C (350°F/Gas 4).

Place the fish heads and bones in a large roasting tin and the prawn heads and shells in another. Season and drizzle 50 ml (1½ fl oz) olive oil into each tin. Bake for 15–20 minutes, or until the fish bones are lightly browned and the prawn shells are pink. Place the heads, bones and shells in a large heavy-based saucepan.

Pour 125 ml (4 fl oz/½ cup) water into each roasting tin, scrape the base to remove any cooked-on bits, then pour the liquid from each tin into the saucepan. Add the halved garlic bulb, bay leaves, parsley stalks, peppercorns, fresh tomatoes, a pinch of salt and another 50 ml (1½ fl oz) of the olive oil. Add enough cold water to cover, then bring to the boil over high heat. Reduce the heat to low and simmer for 1 hour, skimming the surface regularly. Strain through a fine sieve and discard the solids.

Meanwhile, heat the remaining olive oil in a large heavy-based saucepan over high heat, then add the onion and sauté for 5–6 minutes, or until golden. Reduce the heat to medium-high, season to taste, then add the carrot, leek, sliced garlic cloves and the chopped parsley. Season again and cook for 15 minutes, or until the onion and leek are tender.

Increase the heat to high, stir in the wine and brandy and cook for 2–3 minutes to evaporate the alcohol. Reduce the heat to medium again, simmer for 5 minutes, then add the puréed tinned tomatoes and simmer for 30 minutes, or until the tomatoes have cooked down to a pulp.

Add the fish fillets and prawns to the tomato mixture and simmer for 30 minutes. Add 2 litres (70 fl oz/8 cups) of the hot fish stock and simmer for another 15 minutes. Remove from the heat, allow to cool a little, then process the soup in a blender or food processor until a smooth purée forms. Check the seasoning and keep warm.

Put the clams and 2 tablespoons water in a small heavy-based pan. Cover and cook over high heat, shaking the pan, for 3–4 minutes, or just until the shells open. Drain the clams and remove the meat from the shells.

Pour the soup into warmed bowls, scatter with the clams and drizzle with a little olive oil. Serve immediately.