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How to Chop an Onion


Chefs can spend many hours of the week in the kitchen chopping onions. While it is a common kitchen chore, many people are intimidated by the task. Luckily, anyone can easily learn to properly chop an onion, and without a tear in sight. To begin, gather an unpeeled onion, a cutting board and a chef’s knife that is at least twice as long as the onion. Make sure your working space is well-ventilated. It is the build-up of sulfuric compounds that causes tears.



  1. Place the onion on the clean cutting board. Place the vegetable so that both ends – the root and the stem – are visible.
  2. Holding the onion firmly, position the blade of the knife so that once you begin cutting, it will slice the onion vertically through both the stem and root ends.
  3. Begin the cut, making sure the blade is lined up properly. Do not complete the cut, but instead move your hand, now holding the knife handle, to the top of the blade. This will not only give you more force behind your cut, but will also ensure that you will not cut yourself if the knife slips.
  4. Continue the cut, slicing the onion in half.
  5. Turn each half cut-side down and cut the top and bottom 1/2 inches from the onion halves. You can discard the cut ends, or place them aside to be used in a stock.
  6. Peel the halves. Waiting until now to peel them is easier than attempting to do it before cutting the onion.
  7. Chop each onion half by drawing the knife through about three or four times horizontally, then again vertically.


This method will leave you with uniform-sized cubes. Depending on how big you want the final cut slices, you can change the number of slices you make horizontally and vertically. If your recipe calls for other chopped vegetables as well, keep in mind that all vegetables should be the same size to ensure all ingredients are cooked throughout.



Comments (23)

You don't cut the root end. That holds it together while you chop.
Phatch: There is more than one way to chop an onion, one way involves leaving the root end on and the other is the way described above.
To hold it together after squaring off the ends, use your thumb and ring finger to hold the sides in, while your index and middle finger guide the blade across the top.
Additionally, to julienne an onion use the same procedure as above but without the lengthwise cuts across the top...
We didn't learn knife skills at pastry school. It is still one of my biggest disappointments with most baking and pastry arts programs. I'm happy to see this How To guide, but it NEEDS more pictures demonstrating each step, especially for those who learn using visuals.
Actually, you can cut the root end, just not all the way. A lot of chefs like this method because you can actually use the entire diced onion. And I would think that holding the onion together would be a little dangerous...
Finkel: You hit the nail on the head. We all learn in different ways. Some people you can teach by audio (telling/speaking to them). others learn by watching/seeing. A good "teacher" will do both. Remember this when you start teaching. You will one day. Never leave room for error. Do BOTH! That was a lesson I learned very early in my career from a great "teacher". On that note....anyone can be an INSTRUCTOR....but it takes someone special to know how to TEACH. Good luck Finkel! Dan
I cut my onion on both sides and runwater over it, it helps keep my tear duct from overflowing ;-)
pictures eliminate any misinterpretation
I agree, the root preserves onion if you don't use entire onion.
Leaving the root end on the onion not only gives something to hold the onion together, but it also holds in the white milky substance that oozes out when you cut off the root end off. This is because there are compounds in the onion that contain sulfur and when they hit the air they transfer into more volatile sulfur compound that when mixed with the water in your eyes turns into sulfuric acid which irritates the eye, tells the brain to produce more tears and it just becomes a vicious cycle. Sweet onions are less likely to cause this because to make them sweet, they are grown in soils that contain less sulfur compounds. That is why certain areas of the country promote their sweet onions.
White onions for the Yucatan recipes....I love the texture and flavor of White Onions.
I often find a combination of a quick paring knife peeling and a mandolin set on julienne brings excellent results.
Definetely, Mandolin is perfect compliment for slicing onions.
I'm with Phatch: you don't cut the root end. Not only does the root end hold it together and stop the spread of juice, but when you pull back the outer peel you don't tear it off, you leave it attached to the root end, which gives you a much better 'handle' on the onion so it doesn't move around on the board. Or . . . you can use your thumb and ringfinger to hold the onion together. If the latter method is used ALWAYS have a small bowl of ice water nearby in which you can preserve the ring finger on the way to Emergency. G-man.
your way is correct, but if you can sent another photos
I've pretty much given up on the horizontal cuts. Since the onion grows in layers, it is essentially "spiral-cut" by nature. Horizontal cuts are great for slicing hands and not much else. I also favor keeping the peel and root together for a better "handle."
@oldarpanet, I totally agree, vertical cuts are safer and achieve the same end result.
It took me two days in a kitchen to realise all the other chefs were just copying what they had been taught and never bothered to actually look at the structure of what they are cutting!
I do use a mandolin occasionally, but TBH I can do it almost as quickly with a knife.
Or you may grab one of your Stewards and show his this post,
Happy July 4th.
In regards to step #3 , I find the way it is explained confusing .
Are we using one hand or two hands ?, it reads like one hand but I think you mean two hands . I suggest before you publish " how to " articles that you proof read numerous times and try out your method by only doing what you have written . I spent many years writing manuals , recipes , procedures , policies etc. and I realized that you must put every movement or step in the document you are writing .
Have a look at how the C.I.A explains techniques , they are pros . Like anything in the kitchen " practice makes perfect " Happy writing !
Re Step #3
I read this as a typo. I assumed it was meant to read "move your hand, NOT holding the knife handle"
to mean keep holding the handle and move the other hand, that now makes sense.
I agree with Cook Not Mad, you do need to read through several times, and a proof readers trick, is to read it backwards which picks up spelling mistakes you might miss because you "Know" what is next and you don't actually read it.
I run a small fan to blow the onion fumes away from my work area. It keeps them from wafting upward into my face. Works perfectly. Also works for jalapeno and other hot peppers.
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