Serves 4-6

In the days of whitebait feasts in Greenwich and along the Thames, a soup called water souchet - made with the larger fish such as flounder caught in the whitebait nets - formed part of the meal.

In all the recipes I've found, even fairly recent ones, it seems a watery affair with lots of parsley. I've played around with the recipe, adding vegetables like leek and fennel and a few potatoes to thicken it a little, and served the improved result as part of a whitebait feast at our newish restaurant the Rivington in Greenwich. You can make it with cheap species like flounder and whiting to achieve a white-fish British version of soupe de poisson.

60g butter
1kg whole whiting, chopped into pieces, washed
1 leek, trimmed, roughly chopped and washed
1 small onion, peeled and roughly chopped
1 small head of fennel
2 cloves of garlic
250g floury potatoes, peeled and chopped
100ml white wine
2.5 litres fish stock (use good quality stock cubes if you haven't any other stock)
1 small bunch of parsley, stalks removed and reserved and leaves chopped
Salt and freshly ground white pepper

Melt the butter in a large, thick bottomed pan and cook the whiting, vegetables and garlic on a low heat with a lid on for 4-5 minutes. Add the potatoes, parsley stalks, wine and stock, season, bring to the boil and simmer gently for 15 minutes. Remove the chunkiest bits of fish, put to one side and leave to cool. Simmer the soup for 45 minutes, stirring every so often.

Ladle out about one third of the soup, bones, vegetables and all, and blend until smooth in a liquidiser. Add it back to the soup and return to the heat for another 10 minutes. Strain the soup through a medium meshed sieve, pushing it through with the back of a ladle and discarding the debris.

Remove any bones from the fish pieces you took from the pot earlier. Add the chopped parsley to the soup and simmer for 5 minutes, reseasoning if necessary.

Put the fish pieces into warmed soup bowls and pour the hot soup over. Serve with crusty or toasted bread.