How can you cut an onion without crying?

In order to prevent crying, it helps to understand why it happens. There is a chemical reaction that occurs when you cut an onion—you damage the onion’s cells, and the enzyme (Syn-ropanethial-S-oxide) that escapes acts as a lachrymatory agent. When that agent hits your eyes, it mixes with your tears to make sulfuric acid, and your tear ducts activate in an attempt to wash out the contamination.

So, that being said:

1. Wearing goggles is the most obvious answer. It may look a little silly, but it’s the easiest way to prevent the onion’s enzyme from reaching the eyes.
2. Sharpening your knife beforehand limits the damage to the onion cells, thus releasing fewer gases.
3. Spraying your cutting board with vinegar slows down the chemical reaction. It does, however, make your onions smell/taste like vinegar.
4. Always placing the cut side down will minimize the chemicals released into the open air.
5. Cutting onions under the kitchen vent will remove some of the chemicals from the air.
6. And finally, try not to form an emotional bond with your onion.

you can chill it in the freezer for a certain amount of time or cut it under water