What about those tears?

As we said earlier, onions don't really make you cry, like in "boo-hoo-hoo." But they can make your eyes tear up.

What causes that? It comes from a chemical process that takes place for just a few minutes when you cut into an onion.

Here's what happens: Your knife breaks open some compartments within the onion's cells. This allows certain chemicals that have been kept apart in the onion to come together and produce a slightly acid vapor. That vapor drifts up and stings your nose and eyes. Your eyes respond by tearing up. But the onion hasn't said anything mean or tried in any other way to hurt your feelings. It was just a chemical event.

The same chemical that stings your eyes, sulfur, is what gives onions their sharp pungent taste when you eat them raw. When you cook onions, however, that sulfur evaporates away. The main flavor element the sulfur leaves behind in the onion is sugar. When you heat that sugar to a high enough temperature, it turns into caramel, just like the caramel you find in caramel candies. That's what gives cooked onions their sweet, succulent flavor.

So, there you are. Now you know a lot about onions. You know why many regard them as one of the most magic of vegetables there are.