If the hard contacts and/or swim goggles solution works, then it seems that the irritation comes from fumes interacting directly with the eyes.
If the clothes pin/breathing through the mouth idea works, then it follows that the irritation comes from breathing the fumes through the nose.
I don’t have a theory on the water/bread in the mouth trick. Also, I don’t recommend keeping a lit match in your mouth. Sounds dangerous to me. I was told once to burn a candle while chopping. I put the candle right there at the chopping board, but it didn’t seem to work.
What’s the concensus on this?
(BTW, My eyes don’t tear up much, but they sting like crazy.)
Actually, the kitchen folklore states that you should hold a wooden, UNLIT kitchen match in your mouth, SULPHER END OUT. A chopstick would work (or not) just as well.
Gorodish, the really cool guy played by Richard Bohringer in the 1981 French movie thriller DIVA, wore a swim mask and snorkle while he chopped onions. You or I might look stupid if we tried this, but then, we’re not Gorodish.
Just rinsing the onion in cold water before chopping (but after peeling) helps. I guess it’s easier than doing the whole job under the tap. Probably works for two reasons: it rinses off some of the volatile oils, and it cools the rest.
A cooking show I saw says their test kitchen prep cooks swear by the burning candle solution, but I’ve never tried it myself.
I have a really hard time with onions and confess to having resorted to swim goggles on occasion. One thing I found that really does work is setting the chopping block next to a lit burner on the gas stove. The heat makes the air above the board move and gets the vapors out of the way. Of course you have to stand somewhat to the side for this to work.
Also, make sure your knives are really sharp. Blunt knives bruise the onion and splash more of the juice around.
Cut the root end off first, and set it on the counter peel side down. Light a wooden match. Stick the non-burning end in the root part, so the root part works as a kind of little candle-holder. Let it burn while chopping the onion.
I have tried burning a candle, but it doesn’t work as well.
Saltire’s method is the one that has worked best for me. I chop off both ends, peel the root (no, that’s not a euphemism!), chop it in half, and immediately run both halves under cold water. If you run your thumb along the cut edge you’ll feel it’s kind of oily. Rub briskly with your thumb until it no longer feels slick, and then chop right on the board. Never had a tearing problem since, and I don’t wear either glasses or contacts.