This is the recipe, adapted from one found on the internet.
Ingredients3 medium potatoes cut into 1cm dice
750g clam meat (I could find only frozen meat, but if you get fresh clams, you will need to steam them open in some water or white wine and strain carefully to get rid of any sand or grit.
2 litres fish stock (hot)
2 tablespoons butter
½ cup flour
1 brown onion, chopped finely
2-3 sticks of celery, chopped finely
4-6 cloves garlic finely chopped
600ml light cream
salt and pepper to taste 3 bay leaves
As much fresh dill as you like
Gently melt the butter, and sauté the onions, celery and garlic, but don’t let it get more than pale golden. The soup has to be white.
Stir in the flour quickly with a wooden spoon, then add the hot stock a dribble at a time, stirring as you go until it’s all incorporate and nice and smooth.
Add the bay and half the dill, then the potatoes and three-quarters of the clams, simmer until the potatoes are soft.
Take out the bay leaves.
Whizz with a stick blender, then add cream and adjust your seasoning.
Add the rest of the clams and simmer until they’re cooked. Just before serving add the rest of the dill.