Take about two pounds of any large fresh fish and cut it into moderate-sized pieces. Slice finely one small onion, a small carrot, half a stick of celery, and half a dozen button mushrooms. Next take a large stewpan and put into it two ounces of butter and three tablespoonfuls of olive oil. As soon as these are blended, add a sliced onion and a tablespoonful of chopped parsley and fry them. Next add the other vegetables and the pieces of fish, being careful that they are quite dry. Sprinkle with pepper and salt, and fry till the fish is slightly browned. Now add three or four sliced tomatoes and about two quarts of boiling water, and let the whole simmer until the fish is thoroughly cooked, skimming carefully from time to time.

When the soup has cooled a little, strain it, and after removing the fish bones rub both the fish and vegetables through a sieve and put them back into the broth. Let the whole simmer for another ten minutes before serving.

Slice a small French roll and bake it in the oven till moderately brown. Put these slices into the tureen and pour the soup over them.

Grated Parmesan cheese is usually served with this soup.