Bouillabaisse

First make the fish stock, heat the olive oil in a large, heavy-based saucepan over a medium heat.

Add the leek, onion, celery, fennel, garlic, tomatoes, thyme and bay leaf, and fry very gently, stirring often, until the vegetables are softened (around 5 minutes). Take care not to let the mixture burn or the stock will taste bitter.

Add the assorted rock fish, boiling water and white peppercorns. Bring back to a simmer and cook for 30 minutes.

Pass the stock through a sieve and season with salt and freshly ground pepper.

To make the soup, place the potatoes, fish stock and saffron threads in a large, heavy-based saucepan. Bring to the boil and cook for 10-12 minutes, until the potatoes are nearly cooked.

Add the assorted fish to the saucepan and simmer for 8-10 minutes, or until the fish is tender. Season with salt and freshly ground pepper.

To serve, ladle the fish soup into a bread bowl or serving bowl and serve at once with aioli or rouille.