The Absolute Best Way to Dice an Onion, According to a Chef

If you’re brainstorming what to make for dinner, then dicing an onion is never a bad place to start. It's the Goldilocks zone in the onion world: bigger than a mince, smaller than a chop. And it’s a wonderful building block of so many meals: soups, stews, salads, sauces, and stir-fries. Which means, by the time you’ve finished, you’re already well on your way to a spectacular dish.

But with all that riding on an onion, you want to do it right. Which is why we’ve asked Test Kitchen Director Josh Cohen to teach us the hands down absolute best way to slice and dice an onion (without shedding a tear!). Here’s how:

1. Sharpen up.

If you'd rather not cry into your perfectly diced alliums, then grab the sharpest knife you've got. "If you imagine the onion cells on a microscopic level, then a dull knife is like smashing through them with a hammer, crushing the cell walls and releasing vapor," Josh says. "If a knife is sharp, it slices through these cells cleanly." In other words, it's time to show your knife some TLC. Looking for a guide? Head here.

2. Stick to the root of the matter.

The root of the onion keeps everything together—if you cut off too much of the root, your slices will fall apart as you dice. “The trick is to just barely trim the root end, so that you can still see that opaque circle,” Josh says. “It’ll make your job much easier.”

3. Peel and prep.

Next, halve the onion through the root and tail ends. Chop off that tail end and discard, then remove all traces of papery skin. Depending on how fresh your onion is, you might want to peel off the first layer as well. "It can taste papery to me," Josh tells me, "but that's just a weird personal preference."

4. Finally, cut up!

Okay, here's where Josh takes a swerve from the customary culinary-school rules. Typically, you'd make two to three horizontal cuts through the onion, stopping before you reach the root to ensure evenly square pieces of onion.

"Maybe if you work at a really detail-oriented kitchen, it'd matter," he says. "But it's just an extra step that I don't think you need. My method looks pretty much the same."

In Josh's method, position the onion so that the root end is facing away from you, then cut vertically into the onion, stopping about four-fifths of the way through. According to Josh, "the root of the onion should still be holding everything together."

5. Take it home!

From here, it's the slicing you know and love. Starting at the tail and moving toward the root, cut across the onion to make tiny, evenly-sized pieces of onion.

Voilà! No mess, no falling apart—and you're on your way to dinner.

Do you have any tips for chopping onions? Tell us in the comments below!