Over the years, I've heard all kinds of tips for how to keep an avocado from turning brown—from leaving the pit in to pressing plastic wrap onto the surface, and from using lemon juice to nonstick vegetable oil spray.
These methods have served me decently well for cut avocado and guacamole, but a couple days in, there was always a weird film of brownish-green slime I'd have to scrape off its surface. (Not exactly begging for a chip to dive in.)
Sure, we could all polish off a huge bowl of guac in one sitting. It could possibly be the only addictive thing on the planet that is also good for you. But there are times when you want to save some for later or make a big batch ahead of time for a party.
And that's when this handy trick I just learned from a friend comes in handy. No brown, no slime, no work. Seriously.