Mayonnaise is the well-known emulsification of drops of oil into a blend of egg yolk, lemon juice, vinegar, water and/or mustard. Mayonnaise contains 80% oil. Prepared at room temperature, mayonnaise can be served with cold as well as hot dishes. If you use fresh egg yolks, be careful: serve the mayonnaise immediately or store in a refrigerator.
Making home-made mayonnaise is actually very easy. It is often said that the proportion of egg yolks to oil has to be measured with utmost precision, but this should be taken with a grain of salt. One egg yolk is actually enough to emulsify three litres of oil! What is more important is the proportion of oil to other fluids (vinegar, water, etc). You can vary endlessly on the basic mayonnaise recipe by using different types of oil, for example.