Taste & Technique is the March book for the Food52 Cookbook group so I’m having another look at it.
The pouring of boiling water over the egg in the aioli recipe has already been mentioned but still puzzles me.
Why am I interested in setting the protein in the whites and how can that help the emulsification process when the white is promptly discarded?
Edited to add that I agree with @Okanagancook that using a squeeze bottle to add the oil is very smart.