Wash the basil leaves thoroughly and lay them out on a soft towel.
On a cutting board, stack the leaves with the largest one at the bottom, and the smallest one at the top - all the stem sides and the tip sides should be aligned. I typically do about 5 to 6 leaves at once.
Then, roll the basil leaves into a tight cylinder. I typically do this along the longest side (so from bottom to top) so you'll get longer slices. You can also roll side to side.
Using a sharp knife (typically the section closest to your handle) - slice them from right to left (or left to right) into tight curls. Loosen up the curls and your chiffonade is ready!
Notes
This recipe also works with other green leafy vegetables and herbs - most commonly, mint, French sorrel, spinach, and arugula.