Ripen on the counter (or in a paper bag* if you want to speed up the process).
Be sure to check avocados often, as they can go from unripe, to perfectly ripe, to soft and moldy before you know it.
As soon as they yield to gentle pressure, you can move them into the refrigerator, where they should last for a few more days.
Depending on how you plan to use them, if you mash them with some lemon or lime juice, the mixture can be frozen for later when making guacamole or dip.
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