An onion will taste differently depending on how it’s cut.
Thanks to our friend Kenji López-Alt at Serious Eats, we learned that if you slice an onion from end to end, it will have a milder flavor than if you slice it across the middle. That’s because cutting an onion releases flavor compounds, and how you slice—with or against the grain—releases more or fewer compounds.
When you cut end to end, or with the grain, you cause less damage and release fewer compounds than when you slice through the middle. Slicing through the middle, or against the grain, causes a greater disruption and leaves you with a stronger, more pungent taste.
So the next time you go to slice rings for your burger, don’t forget you’re also signing up for a stronger flavor. If you want something less intense, cut it the other way. And with that, you’ve peeled back yet another layer of the onion.