Egg yolk is the glorious yellow center of an egg, containing most of the nutrients as well as the fat and the cholesterol. Whether that color is pale yellow or deep orange depends on the diet of the hen.
In cooking and baking, egg yolks are prized for their ability to help ingredients blend or emulsify. They play this crucial role in sauces, such as mayonnaise and hollandaise. Yolks also thicken and add richness to all kinds of custards, from crème brûlée to flan.
Most recipes call for large eggs. If no size is specified, assume large. 1 large egg yields 1 rounded Tbs. yolk; 1 extra-large egg yields 1-1/3 Tbs. yolk; 1 medium egg yields 1 Tbs. yolk.
When substituting a large number of different-sized egg yolks for large egg yolks, measure by volume rather than number of yolks.
Getting a little egg white in your yolk is not as dire as getting a speck of yolk in your whites.
Store separated egg yolks in the refrigerator but use within 24 hours.