To solve your problem, firstly we need to know why the onions irritate our eyes. The root and shoot of the onion known as the basal plate-contains enzymes that are released when cut into. When these enzymes are mixed with water, they create a sulfuric acid, and it's that acid that irritates our eyes. The best way to avoid these annoying tears when chopping is to stop those acids from reaching out olfactory and tear duct nerves. So you are recommended to chop the onion while it is submerged in water. Hope this helpful.
Place a bowl of water very near the cutting board where you will be cutting the onion.
Cut off the top of the onion.
Remove the skins.
Slice the onion across almost to the root for slices.
To dice the onion; cut it in half lengthwise and slice lengthwise all the way across as shown (almost to the root of the onion.)
Turn the onion around and slice the sides as shown.
If you pour the water into a glass and drink the water it will probably taste like an onion. ( If you have a strong onion.)
My method was the water trick by itself until I learned how to cut it this way. I like the idea of using water with this method for double protection.
Before we get to the answer, it's important to know why we tear up when cutting raw onions in the first place.When onions grow underground, they absorb the sulphur from the earth, which creates a class of volatile organic molecules called amino acid sulfoxides. Crushing the onion cells under the pressure of a knife releases the amino acid sulfoxides to form sulfenic acids, which then reacts with the air to create a volatile sulfur compound that wafts towards your eyes. When the gases hit your eyes, they create a burning and stinging irritant in your eyes, and your eyes naturally tear up in an effort to wash the irritating sensation away.The most effective way to cut an onion without shedding tears (other than to buy them pre-chopped) is to wear swim goggles. If the idea of looking like an Olympic swimmer in the kitchen is too silly for you, you can try chilling the onion before cutting, lighting a candle nearby, sticking a piece of bread in your mouth, or running a fan that will blow the onion fumes away from your face.