If you need an avocado in a hurry, like when you want to whip up some last-minute guacamole, finding the fruit rock-hard is a huge disappointment. Don't panic—there are several ways to ripen an avocado fast.
In the Microwave
Poke the avocado with a fork several times. Wrap it in a paper towel to retain the fruit's moisture, and place in the microwave. Heat for 30 seconds on medium-high power. Remove the avocado and gently press on it to check for firmness. If the avocado hasn't softened, put it back in the microwave for another 30 seconds.
In a Paper Bag
Place a dry avocado in a brown paper bag or newspaper and leave it on the kitchen counter. The avocado should be soft within three to four days, but adding a banana, apple or tomato to the bag hastens the process.
On a Windowsill
Place the avocado on a windowsill in the sunlight. It should ripen within a day or two.