Holy basil ‘Kaprao’ in Thai is a commonly used herb in Thai cuisine. It has originated from the Indian subcontinent where it has important religious and medicinal uses and from there it had spread to southeast Asia. The flavor and scent are distinct and are described as peppery with notes of clove or mint. I personally find it a bit nutty too.
The plant is a small shrub, stems are hairy and leaves have a gently jagged margin. There are a green and purple varieties, both of which are used for cooking, The flavor of the purple variety is often a bit stronger.
Holy basil is used in some of the most popular street dishes including ‘Pad Kee Mao’ and ‘Pad Kaprao’ which is a local favorite stir-fry in Thailand of meat or seafood with garlic, chili and holy basil. Holy basil is an entirely different herb from Thai basil and therefore you should not substitute one with the other.