What Is the Best Way to Cut an Onion?

The cookbook author Kenji López-Alt dives deep into a question of his own, with computer models and all.

In this month’s column, the cookbook author Kenji López-Alt answers a question of his own: What’s the mathematically best way to cut an onion?

I didn’t go to culinary school. My first real instructor was a book, specifically Jacques Pepin’s “La Technique.” In what feels like a precursor to today’s internet videos, it demonstrates every essential French technique with thousands of hands-only photographs. The onion-cutting method I learned from it is the same one taught at top Western culinary schools, and it’s the method used by most of the cooks at every restaurant I’ve ever worked at.

You trim off the onion top (the side opposite the hairy root), then split the onion from end to end. Next, you peel the resulting halves — Mr. Pepin has told me that he also likes to remove the first layer, as it can be tougher than the rest — and lay them flat on the cutting board. There’s nothing particularly contentious so far. The next step is where disagreements creep in, but we’ll get back to them.