Wash the basil leaves well and make sure they're fully dry (I try to do this in advance).
Stack 8 leaves on top of each other, and roll them tightly the long way.
Use your left hand to hold the leaves in place (make sure to curl your fingers like a claw and tuck your thumb behind them).
Hold the knife in your right hand so that your thumb and forefinger are gripping where the blade meets the handle and the rest of your fingers are gripping the knife and slice thin ribbons from the end of the roll (as though you were slicing a jelly roll).
Sprinkle the basil over your meal as a garnish, over a salad or into whatever you're cooking and enjoy!