J. Kenji López-Alt, a professional chef, has spent years studying the fine art of boiling eggs. Although he written about the subject in the past, López-Alt is updating us with the latest research.
And, yes, he means data-driven research. He's not speaking from just anecdotal experience.
López-Alt informs us that the age of the egg doesn't really matter, nor does adding vinegar or salt help make the eggs easier to peel. What does help is setting the eggs in the water after it's boiling to prevent the white from fusing to the shell. He also suggests using a needle to puncture the air pocket to relieve pressure inside the egg during cooking.
In this demonstration video, López-Alt demonstrates his perfect 9-minute eggs, which peel cleanly and without any difficulty.
-via Laughing Squid