I cried over onions for thirty years and treated it as the cost of cooking. Somebody told me to put them in the freezer for fifteen minutes first.
It works. Not perfectly, but enough that I do it every time I’m facing more than one.
Why Onions Make You Cry
Cutting an onion breaks cells and releases enzymes that produce a volatile sulphur compound. That compound floats up, meets the water in your eyes and turns into a mild acid. Your eyes flush it out with tears.
Everything that helps works on one of three things: slowing the reaction, stopping the gas reaching your eyes, or getting it away from your face.
What the Freezer Does
It slows the reaction down. Cold enzymes work more slowly, so less of the compound is produced and it is released more gently.
Fifteen minutes in the freezer, or thirty in the fridge. You want it cold and firm, not frozen — a frozen onion is hard to cut and goes mushy when it thaws.
This is the single most effective thing I’ve found and it needs no equipment.
The Other Thing That Actually Works
A genuinely sharp knife.
A sharp blade slices cells open. A blunt one crushes and tears them, which ruptures far more cells and releases far more of the compound.
If you only change one thing and you don’t want to plan ahead, sharpen the knife. The difference is bigger than most of the folk remedies.
What Else Helps a Bit
Cut near an extractor fan, or with a window open, or with a small fan blowing across the board. You’re moving the gas away before it reaches you.
Leave the root end intact until last. The root has the highest concentration of the compounds, so cutting it up first makes the rest of the job worse.
Cut it under cold running water — effective, but awkward and you can’t see what you’re doing.
Wear glasses. Swimming goggles genuinely work if you don’t mind how it looks. Ordinary glasses help a little.
What Doesn’t Work
Holding a spoon in your mouth. Chewing gum. A wet paper towel on the board. Lighting a candle nearby.
These come round constantly and none of them stand up. The candle one has a shred of logic — a flame does burn some volatiles — but at the distance you’d actually put a candle it does nothing you’d notice.
Which Onions Are Worse
Older onions are worse than fresh ones. Yellow and white onions are worse than sweet varieties like Vidalia. Red onions sit in between.
So if you have a choice for something raw, sweet onions will treat you better.
The Combination I Use
Fifteen minutes in the freezer, a sharp knife, root end last, extractor fan on.
With all four together I can do three onions without a single tear, and it costs me nothing but remembering to put them in before I start everything else.
