Unlike most fruit, avocados ripen off the tree, not on it. Once picked, mature avocados typically take three to eight days to ripen. Producers ship them when they’re still hard to prevent damage to the delicate fruit. This means preparing a dish with fresh avocado takes a couple of days of planning to ensure you have a nice ripe fruit.
Place the avocado on the counter out of direct sunlight or in a brown paper bag.
Leave the avocado sitting out at room temperature for three or more days as needed.
Check the avocado daily by applying gentle pressure to the fruit. A ripe avocado will give slightly to light pressure. Avocados that give completely are overripe.
After ripening, avocados taste best raw such as in guacamole or salads. However, they quickly discolor when exposed to air. To prevent this, store your sliced avocado in tightly wrapped plastic so that no air can reach it.
References and ResourcesGood Housekeeping: How to Ripen Avocados
Food.com: Kitchen Dictionary - Avocado
Aggie Horticulture: Avocado