You can store this guac recipe in the refrigerator for a couple of days in an airtight container. I like to make sure the dip fills the container, so that the top of the container touches the surface of the dip. Or you can press some parchment paper or plastic wrap onto the surface to help keep it from turning brown. I’ve read several other techniques, such as placing an avocado pit in the dip, adding a layer of water on top, or laying an onion half (or onion slices) on the top. I haven’t tried these, but please let me know if you do! As I mentioned above, tomatoes can make the dip runny faster, especially if you include the core, juice and seeds. So don’t! Or skip the tomatoes if you want to make the dip last longer. Finally, I’ve had some decent luck extending the life of my dip by simply scraping the brown layer off the top and eating any green, fresher looking dip that’s left. It’s not as good as fresh, but definitely edible.