Whether you’re browning, caramelizing, pickling, or eating ’em raw, cooking with onions means that they’re going to need to be chopped, and chances are, most home cooks are dreading the task. Stinging eyes and tears running down your suddenly frowning cheeks — it’s a familiar scene. Luckily, thanks to one quick home cook hack, you can save the tears for your Oscar close-up (and keep your swim goggles in the drawer). Just lay a damp paper towel across your cutting board before you start chopping.
Unless you’re Mitch Hedberg (who once quipped, “When I’m cutting onions, I’m sad. Because the plight of onions, it’s sad. But people don’t realize I’m crying — they think I’m just reacting,”) a wet paper towel is all that stands between you and cooking comfortably. The wet paper towel will absorb all those irritating “onion fumes” before they reach your delicate eyeballs. For extra protection, tear off three or four sheets and fold them after wetting, creating a strong magnetic “sponge” to shield your eyes from peril. Seems too simple to be true? To understand why this tip works, it’s helpful to know why onions make you cry in the first place.
Stop syn-propanethial-S-oxide in its tracks
During their tenure in the dirt, onions absorb a lot of sulfur. They suck all that sulfur into their amino acids, and there it stays until you cut those tender molecules open with the blade of your kitchen knife. When the sulfur-packed amino acids meet the liquid enzymes of the onion, the resulting compound is a sulfenic acid that becomes the chemical syn-propanethial-S-oxide. Syn-propanethial quickly evaporates into the air and (you guessed it) right up into your dewy eyeballs. Your tear glands automatically react to protect your eyes from the irritant by flushing it (the same reaction that happens with smoke exposure). Most importantly, syn-propanethial-S-oxide is drawn to water. But, by laying down a wet paper towel on your cutting board, it’ll be drawn toward that instead of toward your wet eyeballs. The paper towel catches the acid before it reaches the atmosphere.
For even stronger prevention, feel free to double up on irritant-redirecting tactics. In addition to chopping on top of a damp paper towel, freezing or chilling an onion before cutting slows the tear-inspiring enzyme from leaking out. Cutting the onion under cold running water also diverts the irritating gas in other directions than straight into your eyeballs. Lighting a candle on the countertop nearby also burns off the irritating gas as it enters the air.
