How to Dice an Onion

The Dice is Right

Diced onion pops up in recipes from nearly every cuisine and culture. But how do you ensure you get a good, consistent dice every time? The key to unlocking an onion is to use what nature gave you. This method uses the onion’s natural geometry to keep things easy and repeatable.

How to Easily Dice an Onion

1. Cut off ¼” from the stem end of the onion – not the root end. Keeping the root end of the onion intact will help with the dicing process.
2. Slice your onion into halves through the root end.
3. Remove the onion’s outer skin and any additional discolored or bruised layers as needed.
4. Place a half onion flat-side down on the cutting board in front of you.
5. Slice through the onion vertically, making parallel cuts that don’t go all the way through to the root end. You want the onion to still hang together from the root end once you’ve made your slices.
6. Rotate your onion 90° and chop through it lengthwise with even cuts. The vertical cuts you made in the previous step will give you diced pieces all the way through. When you reach the root end you can place that face down and dice some additional pieces, or discard it.
7. Repeat steps 4-6 with the other half of your onion.

Some guides will recommend using a horizontal cut or cuts without rotating after you do your vertical slices toward the root end. We’ve had mixed success with this method; it results in a somewhat more even dice, but you should only attempt it if you’re confident in your knife skills and you’re working with a larger onion. Small onions can be finicky when you’re trying to get a good horizontal cut, and your dice will be small regardless.

The methods discussed here result in a consistent dice every time, and can easily be adapted for onion slices or minced onion. For slices, skip the step where you make vertical slices toward the root, and simply slice your onion into half-moons. For minced onion, take your diced onion and make small piles, then finely cut each pile repeatedly until your desired consistency is reached.

How to Cut an Onion without Crying

If you’ve ever chopped an onion, you’re probably shed a few tears over it…but why is that the case? It turns out that onions make us cry thanks to a natural defense against being eaten. When the cell wall of an onion is broken – say, by a knife being used to slice and dice, or the teeth of a hungry animal – the onion releases chemical compounds called lachrymatory factors that are natural irritants. When those get in your eyes, the waterworks start.

So what are the best ways to avoid getting teary-eyed when it’s time to cut an onion? First and foremost, make sure you’re using a sharp knife. At the microscopic level, a dull knife will still cut an onion, but it will crush more of those onion cells in the process, and that releases more tear-causing chemicals. A sharp knife will glide through as few cells as possible, minimizing the tear factor.

There are plenty of urban myths about how to further reduce your onion-eyed discomfort, from holding a spoon in your mouth (goofy), to slicing underwater (dangerous), to putting a matchstick up your nose (dangerous and goofy). We definitely don’t recommend those. But there are 2 methods we’ve found to be effective.

First, if you’re sensitive to those lachrymatory properties, choose onion varieties that have the fewest of them. Sweet onions and shallots aren’t tear-free solutions, but they’re definitely a less eye-watering choice compared to white, red or yellow onions. Second, chill your onions before slicing. A half-hour blast in the freezer can help slow down the release of those tear-causing compounds, sparing you a few sniffles.

Use Your Onion-cutting Skills & Find More Tips

Now that you’ve mastered the art of the onion, it’s time to put your newfound abilities to good use with some recipes featuring – you guessed it – diced onion. Check out meal planning selections, our tips on how to make cooking easier, or browse 101 simple cooking tips to further build your skills in the kitchen.