Call me a wimp (my wife does), but onions make me cry. You know what I'm talking about, right? About 10 seconds after you slice into one of those gorgeous, all-important alliums, you get a bit verklempt.
Instead of turning away to discuss how the Cold War was neither cold nor a war, I decided to figure out how to stem the tide. A quick bit of research reveals that the culprit is a sulfur compound that the plant absorbs from the soil. As you slice through the onion, cell walls are ruptured, and the sulfurous assault begins.
Once the vapors reach your eyes, the compound reacts with the water in the tears already coating your eyeballs, creating a mild sulfuric acid. That's right, onions give your eyeballs the old Harvey Dent treatment.
A bit more reading revealed a host of methods, both scientific and exceedingly not so, for preventing the tears. I decided to give a few of them a try, to see which, if any, is effective. A mound of onions and many tears later, here are the results.
5. Bread in the teeth. That's right, you're supposed to hold a slice of bread between your teeth while slicing the onions. I chose a piece of rye bread, as it was the only loaf I had that wasn't a bit gone. I didn't exactly have high hopes for this one. The going theory is that the bread absorbs the odors before they can reach your eyes. Given that the molecules of sulfur compounds can almost certainly squeeze between the fairly open crumbs of a slice of rye bread with ease, I figured it for bunk. Imagine my surprise when I finished slicing with nary a tear. Perhaps the scent of caraway confused my brain enough to interrupt the tear-making process, or perhaps this was a weak onion.
4. Light a candle. With flames flickering in the periphery of your cutting board, the chemical culprits are supposed to be incinerated before they can do their watery work. Nope. Not at all. Plus, I only had Christmas-scented candles, and the aroma of fruit-cake and onion is a truly unpleasant mix.
3. Onion goggles. Yes, they make these. No, I didn't buy them. I did, however, don a pair of my kids' swim goggles. The principle here is simple. You are quarantining your eyes from the sulfurous compounds. If they can't reach your eyes, that can't create sulfuric acid on them, and the issue goes away. It works perfectly, but feels ridiculous.
2. Blow 'em off. A running fan is intended to blow the fumes away as soon as they escape, and so it does. This was actually highly effective. It did, however, send onion skins skittering all over my table and onto the floor. Perhaps next time I'll peel the onions before switching the fan on. 1. Give them a chill. If you put onions in the refrigerator for about 30 minutes prior to chopping, the cold slows down the chemical reactions responsible for the irritant, and you are left tear-free. This is the only one of the above methods I would ever employ again. Maximum effectiveness, minimal ridiculousness.
Overall, I think it's probably kind of silly to worry too much about it one way or the other. Unless you're chopping six quarts of onions (which, incidentally, I did), you can battle the tears in a much easier way. Keep your knives sharp, and use proper knife skills when chopping onions. The sharp blade will glide through the onion, rupturing fewer cell walls and releasing less sulfur.
Technique will help you slice the onion both more quickly, and in a manner less likely to cause the juice to spray all over. Or, you could always put on safety goggles and chomp a slice of bread. Just be sure not to ignite the bread with the candles you've got going.
Now, what to do with all those onions. . .