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  • The Chopping Blog

Dry Your Eye: How to Chop Onions without Crying

Posted by Josh on Aug 1, 2016
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A very kind and tolerant person once said “There are no stupid questions.” I think there are lots of stupid questions, like “Will this holographic Charizard card be worth enough for retirement?” or “Do I have to buy a gift for EVERY anniversary?” Thankfully, there’s a place you can go to have all your stupid questions answered. Not by professionals, not by experts, but by unidentified people on the internet! 

Yahoo! Answers is the forum that allows anyone to chuck a javelin of inquiry into a field of random web surfing know-it-alls with the hope that they strike at least one person who won’t blame their simple plumbing question on the Ghosts. 

So naturally, sometimes, good hearted grandmas and doomsday preppers…or anyone else who hasn’t changed their homepage from Yahoo! set afloat a genuine plea for help into the expanse. It’s those questions I seek out, hoping to keep one more steak from burning, one more fork from going in the microwave, and one more guy from sleeping on the couch. Because I have culinary knowledge… and Google.

Today’s question comes to us from Anonymous who wants to know “How to decrease crying when cutting onions. My eyes start to sting like crazy and I have to blow my nose a lot. Any neat ideas?”

I totally feel Anonymous here. I weep when I cut onions like a baby that stubbed his toe while watching The Notebook. I’m excited to see what solutions the internet has for me, so I got a bag of onions, put on some Adele, and prepared to make it rain. 

Cut an Onion

"Some chefs fill a bowl of water up and keep it close by, personally I tried this and it did help a bit.” - Anonymous

So I filled up my largest bowl and set it next to my cutting board. It ended up being super effective at catching my tears before they got all over my counter. I’m not sure what I was expecting, but all I really got was a salty bowl of water. 

"I've just heard this recently so I can't vouch for it but I've heard it does work. Cutting the onion near an open flame (candle) stops it.” - Patricia 

As much as I love combining fire and knives, I have my doubts. But I lit my favorite Yankee Candle (Line-Dried Cotton) and got to cutting. Sure enough, the kitchen smelled amazing and I was crying like that time my dog Booger ran off to join the circus. 

At this point, I decided to give my tear ducts a break and take a look at what actually causes you to cry when you chop onions. It turns out that when you slice into an onion you are crushing the cells and releasing amino acid sulfoxides which form sulfenic acid. Enzymes from inside the onion are now able to mix with the sulfenic acid because the cellular membrane has been cut and that produces propanethiol s-oxide, which is the sulfur compound that creates sulfuric acid when it reacts with the water in your eyes. When you add heat to the onion however, you deactivate the enzymes preventing the chemical reaction and eliminating the tears which is why you only cry when dealing with a raw onion. 

So is there an effective way to keep the sulfenic acid from mixing with the enzymes? Not really, but you can limit it as much as possible by using a sharp knife that will damage as few cells as possible when cutting and by storing your onion in the fridge ahead of time which will slow down the chemical reaction a bit. Your better bet is to keep the propanethiol s-oxide from ever reaching your eyes with a pair of goggles or by using a fan. I tried cutting my onion by putting my cutting board on the stove and turning on the hood vent and found that it was actually very effective. 

I hope these tips limit the tears and keep you cutting and slicing for your favorite recipes. Here’s one of mine for a fresh summertime guacamole featuring red onion.



2 large avocados

1/2 large red onion, diced

1 lime, zested and juiced

1 small jalapeño, diced

1/2 teaspoon cayenne

1 tomato, seeded and diced

2 tablespoons chopped cilantro

1 clove garlic, minced

Toss diced avacado in bowl with lime juice to coat and then strain off any extra. Mash avocado to desired consistency and add in cayenne, onion, garlic, tomato, jalapeno, and cilantro. Top with lime zest and an extra pinch of cilantro. 

Want tips on how to sharpen your Knife Skills? Take one of The Chopping Block's upcoming classes and download our free Knife Skills 101 guide.

Knife Skills Guide

Topics: knife, Knife Skills, chop, onion

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