Creating a chiffonade of fresh basil is easy and it can be done ahead, if stored properly. Gently rinse and dry your basil leaves. Stack the leaves vein-side down and roll the stack up widthwise (like you’re making a cigar). Using a sharp chef’s knife, thinly slice the leaves, then unravel the slices into thin ribbons. Use them now or store them in the refrigerator for up to 24 hours, wrapped in a piece of paper towel and stored in a plastic bag.
Also, when you’re preparing a sauce that uses a hefty amount of freshly chopped basil, although you shouldn’t chop it ahead, you can create a chiffonade in advance. Simply run your knife over the ribbons just before adding it to your sauce.