How to Prevent Onion Tears, the Japanese Way

Have you ever tried to slice an onion and ended up with heavy tears flowing like you just watched Grave of the Fireflies again? Onions are full of both flavor and eye-irritating compounds, so onion tears have always been an inevitable part of the journey towards good food—until now, that is. Japanese researchers have developed a new tear-free onion, and it’s not just some quirky novelty. In 2013, the research behind the onion earned an Ig Nobel Prize in Chemistry. A decade later, farms in Hokkaido are getting ready for some major expansions, with plans to expand sales to 5 times the current volume within three years.

What Is the Smile Ball Onion?

Thanks to careful selective plant breeding aimed at weakening certain enzyme reactions, the “Smile Ball” onion has one simple claim to fame: it doesn’t sting your eyes when you cut it. But home cooks may enjoy some of the other aspects of this unreactive onion, too. Its mild flavor is actually subtle enough to bite into raw, so chefs who usually soak their raw onion in water to remove any harsh flavors can skip that step, and toss it straight into salads. That’s a win for busy kitchens, and it also helps maintain the onion’s water-soluble nutrients that might otherwise wash away.

Where Did Japan’s Tear-Free Onion Come From?

An onion that doesn’t make you sob obviously appeals to a wide array of cooks, but the friendly Smile Ball wasn’t developed by some home cook with a gardening hobby. The onion’s story starts back in the 1990s, when researchers at House Foods Group were developing recipes for shelf-stable curry and noticed something they found strange. Sauteing onions and garlic together, it seemed, sometimes turned the mixture green. Investigating that mystery led to the discovery of an enzyme connected to onion pungency, and their research was important enough to be published in the journal Nature in 2002. Years later they took it one step further, figured out the enzyme reaction pathway, and asked an important follow-up question: what if we bred an onion where that reaction doesn’t really kick in? The result was Smile Ball, successfully developed in 2012.

Right now, Smile Ball grows best north of 41° latitude, which means that within Japan, it grows best in Hokkaido. But with sales climbing (48 tons in FY2023, 124 tons in FY2024, with 180 tons targeted this year) farmers and researchers have been working together to continue refining cultivation methods, and allow the onion to handle heat and drought, making it easier to expand production. They’re hoping to sell around 1,000 tons by 2029.

Ready to try Japan’s new miracle onion? Expect to see it soon in Hokkaido and Tokyo supermarkets, priced around 278–298 yen for two large onions—about 1.5x the price of a standard supermarket onion in urban Japan. If the attempt to scale up production succeeds, “tear-free” onions might finally stop sounding like a fantasy and start looking like a standard grocery option.

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