Considered sacred in India, holy basil is used heavily in Thai and Vietnamese cooking. It offers an intense aroma that is similar to that from cloves along with a mild peppery bite and subtle licorice notes. The herb is best known for its use in drunken stir fry dishes from Thailand. In fact, if you want to make this type of Thai food, holy basil will be an important factor in getting the right flavor; however, it may not be the easiest herb to find. If your local Asian market is out or you need some right away, consider one of the substitutes.
Your best bet: Mediterranean basil
It is estimated that there are between 50 and 150 varieties of basil in existence; the most popular one for use in Western cuisine is the Mediterranean basil. It is thus the easiest to find. Mediterranean basil has other names such as Italian basil, Genovese basil and sweet basil. This herb is well known for its role in Italian cooking where its flavor is used for pasta sauces, pesto and a vast range of dishes from lamb to salads. Mediterranean basil has the same peppery note that you get from holy basil along with some of the minty, clove-like notes. There are hints of anise and licorice as well.
Mediterranean basil complements most of the other herbs and spices that you would find in a dish that requires holy basil. Start with exactly the same amount that the recipe requires for holy basil and increase to taste.
A decent second choice: Thai basil
Thai basil is another variety of the herb that is popular in Asian cuisine; in fact, it is used in some of the same stir fries that require holy basil. Because holy basil is not always easy to find, many Thai restaurants in the western world use Thai basil instead. It is similar to holy basil in that it has many of the same flavor notes, including the strong clove flavor and the slight pepperiness. Thai basil is also used in a variety of stir fry dishes, just like holy basil. It is an excellent substitute in that it has a closer resemblance to holy basil than the other substitutes listed here. When using Thai basil in place of holy basil, add exactly the amount that your recipe requires for holy basil and increase to taste.
In a pinch: Oregano
Oregano is a member of the mint family, just like basil. It has a distinctive flavor with pepper and clove notes that are like those in basil. Unlike the other substitutes in this list, oregano is best used dry since the fresh leaves can be a little too pungent and aggressive. Use about half the amount of oregano that your recipe requires for holy basil and increase to taste.
Rosemary is another member of the mint family that has a lot in common with holy basil. Not only is it highly aromatic, it can pair well with most of the other flavors that go into dishes requiring holy basil. Note that the pungency of rosemary means that you need less of it to provide the same level of flavor. Start with about a quarter of your recipe’s requirement for holy basil and increase if necessary.
Fennel is not a mint, but it does offer a mild licorice flavor that can make it an effective substitute for holy basil. Fennel is often used as a vegetable rather than purely for flavoring dishes, which means that it can be an effective holy basil replacement in stir fries.