I am crazy for lemon basil with its exquisite fragrance (you’ve guessed it, lemony) that seems somehow so much more nuanced than sweet basil. It is often used with fish, for which it is a natural pairing, or tossed into soups and salads. The delicate leaves (and flowers too if they are on the stem) are added at the last minute to finish off a dish. Other basils native to tropical Asia can be substitutes. Thai basil, with its anise scent, is usually the easiest to find. Purple, holy, Greek, cinnamon or even sweet basil are fine to use too and each will bring their own character.