How to chop onions without crying - How To

Jul 18, 2025

Because crying over vegetables isn’t worth it.

Onions are delicious, and the base ingredient of almost every savoury dish. But just as beauty is pain, cooking with onions is usually bound to end in tears. Or at least start with them. But why do onions make you cry, and what can you do to stop it from happening? Sharpen your knives and save those snorkelling goggles for your next tropical holiday – we’ve got the answer, and the solutions.

Chopping onions — It’s time to cut the drama.

Why do onions make you cry?

Onions are bulbs that mature underground. This makes them an easy-to-find tasty snack for creatures like rodents and other burrowing animals. Over time, the onion has evolved to develop a special chemical defence mechanism, to protect itself from being eaten. When their skin is broken, the onion releases enzymes and sulphur compounds, which combine to form a chemical known as syn-propanethial-S-oxide. This is a volatile chemical, which means it quickly turns to vapour, and rises up from the surface of the cut onion.

When this chemical hits your nose and eyes, it stings. Your brain senses that your eyes are in danger, and triggers the tear response in an attempt to wash the danger away.

So don’t be mad at onions for making you cry. They’re just trying to protect themselves.

Crumbed onion rings with roast garlic aioli

How to cut onions without crying – step 1: use a sharp knife

A well-sharpened, good-quality knife will damage fewer onion cells as it chops, which means the onion will release fewer eye-stinging irritants. A dull knife is more likely to crush the onion as it chops, increasing the release of chemicals, and thereby your tears.

How to cut onions without crying – step 2: chill them

If you pop your onions in the freezer for a few minutes (don’t freeze them solid – frozen onions will turn mushy when you cook them), this will slow down the release of those enzymes and compounds that produce the tear-inducing chemicals. Here’s where step 1 will come in handy, too. A sharp knife will help you chop the onions faster while they’re still cold from the freezer.

How to cut onions without crying – step 3: ventilate

Turn on your overhead fan, if you have one, open doors and windows and get some fresh air flowing through. Or set up a little portable fan right next to your work station. This will help blow those irritating chemicals away, rather than into your eyes.

How to cut onions without crying – step 4: stand back

Most people tend to bend over the chopping board as they chop, but this puts your eyes right in the line of fire when you’re chopping onions. So stand back a little. The stinging chemicals travel upwards, so they’ll be less likely to hit your eyes if you’re not leaning right into their flow.

Related recipe: Onion tarte tatin

How to cut onions without crying – other methods

Some swear by soaking halved onions in a bowl of cold water for a while before chopping. But this can lead to less flavour in your final dish, and a less crispy onion texture, if that’s what you’re after. Others swear by chopping onions while holding a piece of bread in their mouth. No one seems to know why this might work – maybe the piece of bread sticking out of your mouth acts as a barrier between the burning vapours and your eyes? Or maybe your brain is so confused as to why you’re chopping onions while holding a piece of bread in your mouth, it forgets to trigger the tear response. Who knows? In a similar vein, some recommend holding a metal spoon in your mouth while chopping onions. The thinking is that your breathing switches from your nose to your mouth, which means less of those chemicals irritating your sensitive nasal passages.

So dry those tears, go forth into the kitchen and tackle those onions with confidence. Perhaps this time, you won’t end up looking like you’ve just finished watching Titanic.