Here’s where it gets weird: frozen red onions turn green. I know, it sounds like a science experiment gone wrong. It’s totally harmless—it happens because of a chemical reaction when the onion’s natural compounds mix with air and cold.
Don’t panic. That greenish-blue tint disappears the moment you cook the onion. It’s like the onion’s way of saying, “I’m ready for soup now.”
If you’re serving the dish to guests, just cook it well, and they’ll never know your onions briefly channeled the Incredible Hulk.
How to Freeze Them Like a Pro
First, peel and chop your red onions before freezing. Nobody wants to wrestle a frozen, rock-hard onion with a knife—it’s a recipe for a trip to the ER.
Spread the chopped pieces on a baking sheet lined with parchment paper. Pop that in the freezer for about an hour until they’re individually frozen (this is called “flash freezing”).
Then, toss the frozen bits into a freezer bag, squeeze out the air, and label it with the date. Pro tip: Write “ONIONS” in big letters so you don’t confuse them with frozen cheese cubes (we’ve all been there).
