Sometimes, you just need to make everything ahead – it’s a potluck, or a kids’ party and you’ll be busy with other things later, or you just want to be relaxed at dinner time.
Guacamole is easy to make ahead (and even yummier, I think, if there’s been a chance for the flavors to meld), but if you just stick it in a container and put it in the fridge, the surface will turn an icky black-brown color. Acid helps, which is why most recipes call for lemon or lime (I much prefer lime in guacamole), but if you use enough to keep the guac from turning color, your dip may taste more like citrus than avocado!
The thing to do is put a piece of plastic wrap on top of the guacamole, and push it down so it’s touching the top of the dip, and then put it in the fridge.
This keeps the air from getting to the guacamole, and keeps it fresh and green. Now, guacamole won’t keep days and days – you’ll want to serve this within a few hours, really. But it will stay pretty!
(This also works for homemade or cooked-from-a-mix puddings, to keep the skin from forming. I kind of like the skin, though!)