Thank you both.
Here’s another mention of feather cutting onion, again for a raw prep.
In the class I took, the flat side of the halved onion was place flat side down, and after each slightly angled cut, you gradually rolled the newly cut side toward the board, so that the edge you were cutting into kept a similar thickness on the outside, and a similar angle toward the middle. We did not remove the center.
Tila calls it lyonnaise.
Here is the ATK story on cutting onions. @greygarious and @Saregama , is this the one you mean?
Must be this one.
