Notice I said ‘fewer tears’ rather than ‘no tears.’ The truth is that there is no practical way to completely eliminate eye irritation when you chop onions. But there are things you can do to drastically reduce it. I chop onions several times a week in my kitchen and I can only think of one time in the last couple of months that my eyes were affected enough to cause tears. It’s not that I am one of those people who seem to be immune to the onion’s noxious fumes. I used to cry just about every time I cut an onion. What changed? I started using a sharp knife and I learned the quickest most efficient way to chop an onion.

First Things First: What Causes the Tears?

Well, there’s nothing like a good dose of sulphuric acid in the eye to cause a few tears! That’s right, I said sulphuric acid. Now before you start breaking out the chemical gloves and goggles, let me explain. The onions themselves don’t contain sulphuric acid. But they do release a gas that, upon coming into contact with the natural tears in your eyes, forms sulphuric acid. Let me paraphrase Alton Brown here because science is definitely not my best subject!

When an onion is cut, the ruptured onion cells release enzymes which break down nearby sulfur compounds into oxides and acids. These re-form to make a gas. This gas moves into your eyes and then mixes with your tears to form sulphuric acid.–from Alton Brown in a Good Eats Moment

You’ll hear and read lots of different information about these onion fumes and a lot of it just isn’t true. For one thing, the gas doesn’t just hide out in the root end of the onion. Cutting out the root isn’t going to magically remove all the bad onion juice. It is true that the concentration is higher towards the root end, but the rest of the onion can release quite enough noxious fumes on it’s own to cause problems. Your best best is to begin cutting the onion at the stem end and work your way back towards to the root end (more on this later).

So What Can We Do About It?

So now that we know what causes the problem, what can we do to alleviate it? There are a million old wive’s tales out there that may or may not help to keep the tears at bay. But after doing some research, I’ve found that there are only a few things you can do that will actually help to combat the nasty onion fumes.

1) Use a sharp knife and work quickly: A sharp knife ruptures fewer onion cells. By using a sharp knife and mastering a method of onion-cutting that is quick and efficient, you lessen the amount of gas in the air and shorten your exposure time.

2) Cut near an open flame: The flame sucks in air and therefore pulls the gas away from your eyes. Although a kitchen candle does have some effect, it works best to be near a gas range with one or two burners turned on. Since I started using method number one, I find that I don’t have to resort to this one very often. But when I do end up with an unusually strong onion and my eyes start burning, I immediately light a match and then light my kitchen candle which is always near my chopping area. The candle has always worked for me but if your kitchen allows you to chop near a gas range, give that a try instead!

3) Chill the onion for 15 -30 minutes before cutting: The reasoning here is that chilling the onion will cause less evaporation, less gas, etc. I haven’t actually tried it because I’m not good at planning ahead! But enough people use this method that I thought I would include it.



4) Spritz the cutting board with vinegar before cutting: According to Alton Brown, this interrupts the chemical reaction and I read in several places that this does actually work. The drawback here is that your cutting board and onion will smell like vinegar. I don’t personally use this method but since it is proven to work, I decided to include it.

5) Cut the onions underwater: Well, this will of course eliminate any gas from escaping into the air and will therefore eliminate the eye irritation problem. But it’s so impractical that I put it on the list just for fun!

As you can see, I only use the first two methods when chopping onions. I won’t tell you that my way is the only way to combat tears, but I will say that it works great for me. The real key to combating onion fumes is to use a sharp knife. You want to make clean cuts that don’t smash and tear the onion. Don’t use a serrated knife or any knife that requires a sawing motion. Even though you can’t see them, try to remember to treat those little onion cells nicely and they will be much nicer to you!

What’s the Best Way to Cut an Onion?

Now we get to the good part! Learning how to chop an onion has been one of the greatest triumphs of my home-cooking career. If you read my last post, you know that onions were my least favorite food when I was younger. Ok, that’s an understatement. I HATED onions. Hated hated hated them! So, it goes without saying that I never learned a good way to chop them. And when I started forcing myself to cook with them, it was always a challenge to get the pieces small enough that the end product would have no discernible onion chunks. I would always end up hacking away at a pile of onion pieces, trying to mince them into oblivion. Meanwhile, tears would be pouring down my face because (as we now know) I was destroying all those onion cells and overwhelming my eyes with sulphuric acid.

Finally I decided that there had to be a better way. The problem was that it seemed like every home cook and Food Network star had a different method of chopping onions! Everywhere I turned, I was given different information. It took a lot of trial and error to become the onion-chopping aficionado that I am now. But it was worth it! I can now say that I love to chop onions! Seriously, I love it. It’s one thing I do in the kitchen that makes me feel like I really know what I’m doing. And that is a very rewarding feeling!

I wish I had my own video to show you because I can’t find a video anywhere that shows you my exact method. But I found a video by Chef Jean-Pierre that comes pretty darn close. The best I can do for now is give you a photo tutorial of my method and then you can watch Chef Jean-Pierre’s video. Between the two, you should be able to get the hang of it!

First, let’s familiarize ourselves with the onion. When you hear someone refer to the root end and stem end of an onion, sometimes it’s difficult to know which is which since the roots and stems are usually no longer attached! It’s important to know which one is the root end because like I mentioned earlier, this end of the onion might release more of that evil gas and we want to keep it intact for as long as possible. This is the root end:

And here is the stem end:

Now the very first thing to do when you’re ready to cut up your onion is to cut it in half. Be careful when you do this as the skin can be slippery! You want to cut right through the stem and the root, like this:

Now that you have your two onion halves, it’s time peel them. First, cut off the stem end:

Now it is very easy to peel off the outer layers of skin:

Now it’s time to start cutting!

You want to start making cuts in the onion without cutting all the way through the root end.

The spacing between the cuts depends on how big or small you want the onion pieces to be. And always make sure to keep the fingers of your ‘helping hand’ tucked out of the way!

As you can see, the onion is still held together at the root end. Now you are ready to make some crosswise cuts!

As you cut across the onion, you’ll see it turn into a perfect dice!

You can change the size of dice by making fewer cuts across the onion.

On the left, I made fewer cuts and ended up with a chopped onion. On the right, I made more cuts, closer together and ended up with diced onion. The sharper and thinner your knife, the easier it is to make more cuts close together.

Now watch Chef Jean-Pierre’s version:

Now I’m sure that many of you have very different methods of chopping onions and keeping tears at bay. Please feel free to leave a comment and let us know what works best for you!

Good luck and happy chopping!

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