Onions are the mortal enemy of facial orifices.
The horror of chopping into a particularly pungent onion is familiar to us all. One minute you’re looking classy in your nicest apron and the next moment you are weeping profusely over the cutting board. You can barely breathe. Your upper lip is covered in snot. Rubbing your eyes makes it ten times worse. You’re overwhelmed by pain and you can’t see, let alone think clearly, so you throw your face under a running faucet and scream like the Browns just won the Superbowl. And now your dinner guests are slowly backing out of your house. The whole thing is just so embarrassing.
There are no two ways about it. Onions hurt. They burn. They sting. Every time you slice, chop or dice an onion, you rip open thousands of cells, stirring up a noxious potion of previously inert chemical compounds. The chief ingredient in this potion is a little molecule called thiopropanal sulfoxide, and it is uniquely prepared to crawl in your nostrils and set fire to your eyes.
But onions are also the most important ingredient in cooking.