How to Chop Onions Quickly and Safely

I know what you’re thinking – “Anyone can chop an onion, why do I need to read a post about it?” And you’re right, anyone who can hold a knife can chop an onion. But over the years, cooking with friends and family members and working in hospitality, seeing other people chopping veg, it’s scary how dangerous some people’s techniques are, and onions seem to baffle people the most.

I have literally seen people holding the knife with one hand, the other hand up in the air like they’re on a rodeo bull, while they smack the onion with the blade, wondering why it’s not chopping up evenly. I’ve seen people cut themselves because the layers of the onion are sliding around underneath the knife and they don’t know how to hold it to keep it secure and their fingers out of the way. I’ve seen people take 10 minutes to chop one onion because they are concentrating so much, trying to get a fine dice, but still ending up with huge lumps, their eyes streaming because they’ve taken so long. And I’ve seen people go through 2 or 3 onions, trying to work out how to get rings or half moons.

So no, you don’t need to read this post, I’m sure you can already chop up an onion. But if you want to be able to do it quicker, safer, get reliable results every time and reduce your waste, give it a read. You might pick up a few tips.

Safety First

It’s really important to have a sharp knife when chopping veg. I know it can be a bit scary thinking “Jeeze, if I slip with this I’m taking my finger off, not just getting a scratch” but if the blade is blunt you’re actually much more likely to cut yourself with it. First of all you feel safer with a blunt knife so you don’t take as much care, but also, you need a lot more pressure on the knife for it to make an incision and you’re in danger of it slipping off the veg and onto a finger. If you have a really sharp blade, it cuts so easily that it’s embedded into the veg before you’ve even started to push down on it, and once it’s in the onion, unless your fingers are directly underneath, it’s not going to slip and cut you.

It’s also really important to chop veg on a wooden or plastic chopping board, not glass, metal or your counter top. A slippery surface will make it so much harder to hold the veg in place, and once your blade has made it through, there’s a danger of that slipping to.

Know Your Onions

To understand why onions are shaped the way they are, you have to understand how they grow. The part of the onion that we eat is the bulb of the plant. The pointy bit at one end is where the stem of the plant was and the hairy bit at the opposite end is the root.

The bulb swells up and grows in the ground to provide the plant with nutrients so it can complete it’s life cycle. Some people struggle to remember which way the circles go inside an onion and end up chopping it the wrong way to try and get rings. But if you hold the onion up the way it would grow – root at the bottom and stem at the top and imagine new layers growing from the root, over the bulb and up to the stem to supply the plant with nutrients, it’ll remind you that the rings run that way, and not from side to side. The root and the stem are also what hold all the layers of the onion together, so keep these intact as much as possible when chopping to stop the layers from sliding around and falling apart.


  • Take a whole onion and cut the stem off, leaving the root intact.
  • Peel off the skin, using the raw edge to help get it started.
  • Use a sharp knife to slice the onion in a downwards motion, starting from the cut side and moving along towards the root, however thickly or thinly you want the rings to be.
  • When you get to the other end, use the root to hold onto the onion and keep it in place while you slice the last few rings.

Half Moons

  • Cut the onion in half, right through the stem and root, leaving half on each side.
  • Use the raw edge to peel off the skin and cut the stem away. Leave the root intact, this will hold all the layers together as you chop.
  • Hold the onion firmly with one hand as you cut in a downwards motion towards the chopping board, starting from the cut side and moving along towards the root.
  • When you get the to the other side, hold on to the root to chop the last few slices.

Finely Diced

  • Using a sharp knife, cut the onion in half, right through the stem and root, leaving half on each side.
  • Use the raw edge to peel off the skin and cut the stem away. Leave the root intact, this will hold all the layers together as you chop.
  • Place a flat palm on top of one onion half, flat side down and slice horizontally half way up the onion until you almost get to the root. Don’t cut all the way through though, we’re keeping the root intact for as long as possible.
  • Then make a few vertical incisions all the way through to the chopping board, towards the root but don’t make them long enough to reach the root.
  • Next, slice vertically in the other direction and the onion pieces will fall apart as you chop, perfectly diced. If you want smaller pieces, just make these cuts closer together, for a chunkier dice, spread them out further.
  • When you get to the end of your earlier incisions, turn the root over so you have the largest flat surface against your chopping board once again and cut around the root.

Still don’t get it? Watch the video below:

Finely Diced Onion Clip

And there you have it – my tips on chopping onions quickly and safely. Happy chopping!

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