I used to treat onions like a biohazard. Goggles, open window, leaning way back like the knife was a foot away from my face. It did not help. My eyes streamed anyway and my dice came out as sad, uneven chunks. Then a line cook friend watched me once and fixed both problems in about two minutes.

Why onions make you cry

Cutting an onion breaks cell walls and releases a gas that floats up and lands in your eyes, where it turns into a mild acid. The fix is either less gas or keeping it away from your eyes. Chilling the onion first does both. A cold onion releases less gas, and the cold slows the reaction. Pop it in the freezer for ten minutes before cutting.

The knife skills part

The crying is half the battle. The other half is cutting it properly so you do not have to rush. Here is the method:

1. Cut the onion in half through the root, and leave the root end intact. It holds the layers together.
2. Peel the skin off each half.
3. Slice parallel to the cutting board, going toward but not through the root.
4. Turn the onion and slice straight down. The pieces fall into a dice.

The tricks that actually stopped my tears

• Cut near a flame or running water. The gas gets pulled away before it reaches your eyes. My stove vent fan works too.
• Wet your knife before slicing. It absorbs some of the gas.
• Breathe through your mouth. It sounds silly but it keeps the gas from traveling up your nose and into your eyes.

When you need a lot of onions

If you are dicing three or more onions, do it under the vent fan on high or in front of a small fan. I do a big batch of caramelized onions every few weeks and the fan is the only reason I can see afterward. A sharp knife matters too. A dull blade crushes the onion and releases way more gas than a clean slice.