Thai Holy Basil is one of many varieties of holy basil or Tulsi as it’s known in India with a distinctive aroma. It’s sharp and peppery, with perhaps a touch of lemon. Many people confuse it with Thai Sweet Basil (horapa in Thai), which is a slightly sharper herb with a hint of liquorice.
There are a few different varieties of Tulsi or the holy basil and the one used in Thai cooking is called Thai Holy Basil or Kra Pao.
Why is it called Holy Basil? Because it is a sacred herb in Hindu ceremonial practices, “Tulsi” means The Incomparable One in Sanskrit. In Hindy mythology, Tulsi represents Lakshmi, wife of Vishnu, one of the most important Gods in Hinduism. However, it is a herb used not just in Ayurveda but also in Greek and Roman medicine. So, as you can imagine, it has many claims to heath; it’s supposed to be a stress reliever, an antioxidant and an anti inflammatory herb.
How is Holy Basil used? Besides for religious purposes as mentioned above, it is a very popular herb in some South East Asian cuisines, for eg, it gives the defining flavour in Thai Basil Chicken Recipe (Pad Kra Pao Gai | ผัดกระเพราไก่).
Substitutes: the bottom line – NONE! If you can’t find it, you can use alternative herbs like Thai Sweet Basil or Mint but the resulting dish will be a different one.