People often ask about Thai basil and whether they can substitute ordinary basil for it. When people say “ordinary” basil, what they usually mean is the Italian sweet basil that is usually found in the UK. To find Thai basil, however, you probably need to go to a specialist Asian store such as Wing Yip (my favourite!).
It can get a little bit confusing as Italian basil is often known in the UK as sweet basil and one of the types of Thai basil is also known as sweet basil – but they are not the same and have very different tastes. Also, there are three different types of Thai basil, so let’s have a look at them.
The first type of Thai basil is holy basil (bai kaprow). It has a purple stem and leaves. It has quite a hot flavour and is used in stir fries. As with most fresh herbs, you add the holy basil just at the end of cooking.
The second type of Thai basil is also known as lemon basil (bai manlak). This one has a light green stem and leaves. It’s used in soups and curries, especially those with seafood. Again, add the bai manlak at the end of the cooking process.
And finally we come to the third type – Thai sweet basil (bai horapha). You can see it in the photo above. Whilst I do use the other types of Thai basil, bai horapha for me is the Thai basil that you need. It has a purple stem and dark green leaves and can be used in all sorts of dishes. It has a very distinctive aniseed flavour, and in my opinion you simply cannot make an authentic-tasting Thai green curry without this Thai sweet basil. Yes, you can substitute Italian sweet basil and make a nice curry but, sorry, it just won’t taste anything like Thai curry. There is no substitute for bai horapha.
The good news, however, is that if you do manage to find it, it’ll keep quite well for a few days in the fridge. Wrap it in kitchen paper, put it in a plastic bag and keep it in the fridge. Alternatively, you can make a sort of pesto out of it. Wash and dry the leaves and blitz in the food processor with sunflower (or other tasteless) oil. Then you can store this in the freezer in an icecube tray. Then any time you need Thai sweet basil, pop a bai horapha icecube in your dish towards the end of cooking.
If you’re interested in Thai cooking there’s more information on my Thai ingredients page.