For a period of time in my childhood, I lived in a house that had an avocado tree growing in the front yard. Human nature being what it is, you can start to take something for granted when it grows on a tree in your front yard.
But not avocados. Even at the age of 7 or 8, I was fully aware of how fortunate I was. Avocados falling from the sky! It was like being one of the Beverly Hillbillies, only instead of black gold, ours was green.
I'd come home from the corner market with an armful of comic books, and sit on the porch eating yard avocados and reading the latest issues of Journey Into Mystery and The Witching Hour.
Selecting and Ripening Avocados
If you don't have an avocado tree, you're going to have to buy your avocados at the store. (If you DO have an avocado tree, send me some avocados.) An unripe avocado will be hard and green. It won't give at all when you squeeze it. But you might as well buy it. It'll ripen just as quickly on your counter as in the bin at the market.
A rock-hard green avocado will ripen in 4–5 days. But if you store it in a brown paper bag along with an apple or banana, it'll ripen in 2–3 days. Apples and bananas emit a hormone called ethylene, which tells the avocado to start ripening. Keeping them in a bag helps contain the ethylene, which is emitted in the form of a gas.
I like to stagger them, so they don't all ripen at once.
For guacamole, you want at least three ripe avocados, so I put three in the bag at a time and keep the rest on the counter. The counter avos will be ready a day or two after the bag ones.
Ripe avocados will yield ever so slightly to a gentle squeeze in the palm of your hand. But subjective terms like "slightly" and "gentle" will only get us so far.
So you can look at color. The skin of a hass avocado will be green when unripe, and gradually darken until ripe when its skin will be glossy and nearly black.
Occasionally an avocado might pass the squeeze test, but when you cut it open you discover that it's soft at the surface, but the flesh within remains hard and fibrous. That's because they were harvested before reaching full maturity. (It happens to the best of us.)
That's one of the interesting characteristics of avocados. They mature on the tree, are harvested, and then ripen after they've been picked.
Really, though, the best way to get good at discerning which avos are ready now versus which ones will be ready tomorrow, or the next day, is to practice. You'll get a feel for it. Inevitably you'll cut one open that isn't ripe yet. You'll try to eat it, and you'll want it to be good, but it just won't. But that's OK. It's how you learn.
Storing Avocados at Home
If your avos are ripening and for some reason you need to slow them down, you can store them in the fridge for a day or two. Similarly, if you have half an avocado and want to store it, just squeeze a bit of lemon or lime onto the surface and wrap it in plastic wrap and store it in the fridge.
Try to get the wrap to hug tightly against the cut surface of the avocado to seal off oxygen, which is what causes cut avocados to turn brown. Citrus like lemon or lime also helps prevent this. (There's also this technique.)
Similarly, if you cut open an avocado and it isn't ripe, squeeze some lime or lemon on it, reunite the halves, then wrap them tightly together and refrigerate. If you're saving half an avocado, leave the pit in the half you're saving. The pit may not possess special properties, but it does prevent the flesh underneath it from being exposed to oxygen.
To store ripe avocados for longer than a few days, mash them up with some lime juice and freeze in a ziploc bag. When you're ready, thaw it in the fridge overnight. It'll be fine for sandwiches or guacamole.