Thai cooking utilises three type of basil: Thai basil, holy basil, and lemon basil. The latter is the most difficult to find outside of Thailand and the first in the list the most commonly available. Thais treat them as three separate entities and so these basils are generally not interchangeable with each other. The fresher the leaves, the more you’ll get out of them; the flavours will dull over time.
Types of Thai Basil
An artist’s rendition of basil (from ‘A Cook’s Guide to Asian Vegetables’)
Thai basil (bai horapha) looks similar to your everyday Italian basil but with purple stems, and the flavour is of bold aniseed. If you can’t find this, you can substitute with Italian basil, although the flavour will be markedly different.
Holy basil (bai gaprow) is a milder variety with jagged green leaves and has a peppery flavour with a clove like undertone. This is a key ingredient in pat gaprow (kaprow/gaprao), which translates literally to fried holy basil. Always enquire at Thai restaurants when ordering this dish to see that they don’t use Thai basil – this is a good way to judge the reliability of the rest of a menu!
Lemon basil / Hairy Basil (bai maeng lak) is the most delicate and least utilised of the three, and needs to be used fairly quickly as the aroma will dull after a couple of days. In the dishes where it’s used (e.g. kanom jin nam yaa) it plays an important role in the overall flavour. I’ve found a worthy substitute to be Vietnamese lemon balm (cockscomb mint), which you can find in some Vietnamese shops in East London (try Star Night, among others). If you can’t find either, omit it from the recipe without replacement.
UK Availability
In London Thai basil is easily accessible in most well stocked East Asian supermarkets. You are likely to find it in Chinatown. Holy basil is a little trickier to find, but if you seek out a Thai supermarket and ring ahead, then you might have luck. Sometimes online retailers Thai Food Direct and Thai Food Shop have lemon basil in stock. They usually have Thai and holy basil as well.
I’ve really been enjoying learning about authentic Thai food! I love regular Thai basil and just buy it in Waitrose (it’s sold with along with all the other “normal” herbs) but have never tried holy or lemon basil.
You can find holy basil sometimes in Chinatown or the Vietnamese shops in Hackney/Shoreditch, but lemon basil is next to impossible to source in the UK. There are a couple of places online that sell it sometimes (listed here: http://www.messyvegancook.com/2014/09/27/recommended-thai-cooking-resources-in-the-uk/)
Thanks! Do you have any recs for vegan-friendly places to eat in Chinatown by the way? We ended up eating there last night but had no clue where was good.
Tokyo cafe is good. Jen cafe does some vegan options (so I’ve been told), and the street food dumpling guy across from there has a vegan vegetable one. Baozi Inn has some good stuff as well. It’s been a few years since I’ve been, but the tofu flower soup thing was ace.