 Do you cry when you cut onions? It's a common irritant for professional and amateur cooks all over the world. It happens because of the plant's defense mechanism. Believe it or not, it prevents it from being eaten. And that defense mechanism works pretty well with most animals. But we humans, we are undeterred. Luckily, a colleague of mine recently spoke to a few experts to see what onion cutting tricks are actually worth the salt.