Boil the onion and salt in the stock. It requires no thickening, as if the potatoes are passed through a sieve and added to the stock they will make it thick enough. Add the parsley after the soup is in the tureen, as it will turn brown if put in too soon. The yolk of an egg, beaten, can be added, if required, to make the soup richer.
CREAM OF SPINACH
1 pint of cold cooked spinach.
1 quart of stock.
Heat the spinach, using a little of the quart of stock with it, and press through the sieve; thicken the rest of the stock and the seasoning, and strain again. It is better to use cayenne pepper instead of black with spinach.
CREAM OF TOMATO SOUP, CALLED TOMATO BISQUE
6 large tomatoes, cut up.
2 slices onion.
2 sprigs parsley.
1 teaspoonful sugar.
½ teaspoonful salt.
1 quart stock.
1 tablespoonful butter.
1 tablespoonful flour.
Cook the tomatoes with the onion, parsley, sugar, and salt for twenty minutes, with a little of the stock. Make the stock and flour and butter into white sauce as usual; strain the tomato, mix the two, and strain through a sieve.
Sometimes add a stalk of celery to the other seasoning as it cooks, and a little cream before serving.
OYSTER SOUP
1 pint oysters.
1 quart rich stock.
½ teaspoonful salt.