|Image from The Kitchn
I used to just use plastic wrap, wrapped as tight as possible. Maybe if you could get it perfectly smooth over every molecule, but that’s not happening! Okay, so I heard about adding the avocado pit to the bowl. Tried that; no help. Adding lime juice or tomato slices on top? Helps a little, but not enough.
One time when I wanted to doggy-bag the last of my favorite restaurant guacamole, and no plastic wrap at hand, I had an idea. I smoothed the guacamole out, then spread a layer of sour cream over it, completely covering it so no green could be seen.
Next day, it was still a bright, fresh green — nice! And I don’t mind stirring a little sour cream into my guac. I wondered if the same thing would work for cut avocados. Sour cream turned out to be a little too soft for this application — but softened butter worked great. Again, you just have to spread it thick enough so no green shows through. Then wrap it with plastic wrap to keep the butter in place.
The reason these both work is because they completely seal the avocado off from any oxygen.
Now I see that The Kitchn has a similar method for keeping guacamole from turning brown: cover it with a half inch of water, in a closed container in the fridge. For up to three days, they say. Because the guacamole is so fatty, it’s not going to mix with the water. The author says, “After I take it out and pour off the water, I stir up the guacamole and the texture is no different than when it was made. In fact, I like the taste of guac after it has sat in the fridge overnight; I find the cilantro and onion flavors are blended better.”
Serious Eats says that you can do the same thing with cut avocado pieces. “I store my unused avocado pieces in a plastic container filled with water in the fridge for up to overnight. Perfect, oxygen-free seal for any shape, and because an avocado is so dense and high in fat, water is slow to penetrate it (it’ll eventually become softer).”
So there you go: all you need to keep the green stuff green is sour cream, butter, or water. I love simple solutions!