Avocados ripen best off the tree, so you'll find that a lot of them are unripe when you shop. Look for avocados that feel heavy. The skin should be dark, with a hint of green, and taut, with no dents.

If avocados at the market are green and unripe, you can ripen them at home. Put them in a brown paper bag out of direct sunlight. Within three days they'll be perfect. Press the skin gently. It will be tender but not too soft.

To work with an avocado, hold it on the board and cut lengthwise around the pit. Hold your hand on top to keep it steady with fingers out of the way. Twist the sides to release the flesh.

Firm-ripe avocados are perfect for slicing and salad. Give it another day, and you'll have one that will be the star of your guacamole.