Cut the onions and parsley fine, and boil with the Peas until all are quite tender, for about a half hour. Then drain. Rub all through a sieve or colander, and add them to the boiling Broth or milk. Do not allow this to boil after adding the Peas. Season and serve with dainty Croutons. To keep hot, stand the Soup on a bain-marie, or kettle of boiling water.