Thickening with Egg

One can thicken a sauce or a soup by adding one or more egg yolks. Here one must be still more careful. The yolk of an egg thickens when it is heated in a liquid to about 62°C/144°F. Above this temperature it hardens and coagulates and the liquid curdles.

Only add the egg to the lukewarm liquid. Put it on a moderate heat, stirring all the time. Dip your finger in the liquid from time to time. When the heat becomes intolerable reduce the gas, keep on stirring and wait for it to thicken. Do not try to make the mixture too thick. You risk disaster. The liquid will certainly thicken as it cools.