Soups thickened with a Liaison of Cream and Yolk of Egg
In thickening soups with a liaison of cream (or milk) and yolk of egg, the eggs must first be well beaten, then the cream should be added to them and thoroughly mixed. When this is done take a tea-cup of hot stock and mix it slowly with the liaison. Strain it all through a fine sieve or muslin, and add gradually to the soup, which must on no account be allowed to boil after the liaison is added, although it should be stirred over a gentle fire until it thickens.
In thickening soup with eggs only, beat the required number of eggs, add a little warm stock to them. Strain, and add gradually to the soup.