As the most important ingredient you can have as a cook, according to the University of Illinois Extension, onions offer versatility not seen in other food plants. You may eat onions pickled, raw, boiled, steamed, french fried, broiled, creamed, baked and fried. While preparing onions, they may cause your eyes to sting and tear up, which happens when propanethial-S-oxide, a sulfur compound, releases into the air. The compound turns into sulfuric acid upon contact with water or tears in your eyes, causing your eyes to burn. Preventing onions from stinging your eyes can help make onion preparation a more pleasant experience.

Place the onions in the freezer for 10 to 15 minutes before cutting them, which slows down the enzymes that create the sulfuric acid vapors.

Leave the root end of the onion on while you chop and peel the onion.

Burn a candle next to the cutting board as you chop the onions, so the gas draws toward the heat of the flame instead of toward your eyes.

Cut your onions using a sharp chef's knife, which causes fewer of the cell walls to become damaged, preventing less of the sulfur compound to be released.

Chop onions under cold water to slow the enzyme production.

Wear safety goggles while chopping or slicing onions to keep your eyes from stinging.