Mayonnaise has a kind of alchemy about its construction when emulsification is successful, an infuriating conspiracy when it fails. Precisely who thought about adding oil slowly to raw egg yolks while stirring with a wooden spoon is not known, though it was almost certainly in France and probably in the 18th century.
A whisk is better than a spoon and an electric balloon whisk perhaps the most reliable and quickest way of getting a good result every time. The ingredients should neither be too cold nor too hot. If you keep your eggs in the fridge, then you should remove them well in advance and bring to room temperature before attempting to make the mayonnaise.
If the mayonnaise curdles you can usually bring it back by whisking the curdled mess into a fresh yolk in a clean bowl though it is better to start the yolk with fresh oil, only adding the curdled mayonnaise when this has started to cohere.
The ratio of oil to egg is not the major issue some recipes suggest. One egg yolk will happily hold
The salmonella issue with using raw eggs in mayonnaise remains a vexing one. The law forbids the use of raw eggs in restaurant kitchens, but at home you can evaluate the risk for yourself. As a general rule do not feed raw eggs to the elderly, sick or pregnant, or to young children. Otherwise we are old enough to live dangerously at our tables if we wish.
© 1998 Alastair Little and Richard Whittington estate. All rights reserved.