Three Basils, Three Different Jobs

Walk into any Thai kitchen and you will usually find more than one basil within reach. They look similar enough on the shelf, but they behave completely differently in the pan, and swapping one for another can change a dish beyond recognition. Learning to tell them apart is one of the quickest ways to make your home cooking taste more authentic.

The three you are most likely to meet are holy basil (bai kaprao), Thai basil (bai horapha) and sweet basil (bai kaphrao — the sweet, aniseed variety often labelled simply as Thai basil in British shops, so check the leaves before you buy). Each has its own personality: one is peppery and fiery, one is sweet and liquorice-like, and one is gentle and herbal.

Holy Basil: The Peppery One

Holy basil, or bai kaprao, has small, slightly serrated leaves with a matte, almost fuzzy surface and a faint purple tinge on the stems. Raw, it tastes sharp and peppery with a hint of clove. Cooked hard and fast, it turns deeply aromatic and slightly bitter at the edges, which is exactly what you want in a stir-fry.

This is the basil for pad kaprao, the minced meat stir-fry that appears on every street corner in Thailand. Heat a wok until it is smoking, fry garlic and bird's eye chillies for a few seconds, add minced pork or chicken, season with fish sauce, oyster sauce and a pinch of sugar, then throw in a large handful of holy basil right at the end. The leaves should wilt but not collapse. Serve it over rice with a fried egg on top, and you have one of the great quick suppers.

Holy basil is also good torn into spicy soups and stir-fried with seafood. If you cannot find it fresh, dried holy basil is a poor substitute — the aroma vanishes. Grow it on a windowsill instead; it thrives in a warm, sunny spot.

Thai Basil: Sweet, Aniseedy and Versatile

Thai basil, bai horapha, is the one with purple stems and narrow, glossy green leaves. The flavour is sweeter and more liquorice-like than holy basil, with a gentle minty finish. It holds its shape better when cooked, which makes it useful in dishes where you want the leaves to stay visible and fragrant rather than melt away.

Use it in:

• Green and red curries — stir a handful through just before serving, off the heat, so the perfume stays bright.
• Drunken noodles (pad kee mao) — the aniseed note stands up beautifully to chilli and soy.
• Thai salads such as yam talay, where the raw leaves add a fresh, sweet edge.
• Vietnamese-style broths and noodle bowls, where it is often served as a table herb alongside coriander and mint.

Because it is relatively robust, Thai basil is also the best choice if you are cooking for people who find holy basil a little too pungent. It is the friendly all-rounder of the three.

Sweet Basil: The Mild Cousin

Sweet basil is the Mediterranean-style basil you will find in supermarkets — large, soft, bright green leaves with a mild, slightly sweet flavour and none of the clove or aniseed punch. In Thai cooking it turns up most often in green curry and in light coconut-based soups, where its softness is an advantage.

Treat it gently. Add it at the very end of cooking or use it raw in salads and garnishes. It bruises easily and turns black in a hot pan, so it is not the one for a screaming-hot wok. If a recipe calls for Thai basil and all you have is sweet basil, you can use it, but add a little extra mint or a strip of lime zest to lift the flavour back towards where it should be.

Buying, Storing and Growing

Look for bunches with perky, unspotted leaves and firm stems. Avoid anything limp or yellowing — basil deteriorates fast once picked. At home, trim the stem ends and stand the bunch in a glass of water on the windowsill, loosely covered with a plastic bag. Change the water every couple of days and it will keep for a week or more.

For longer storage, wash and dry the leaves, then freeze them in a bag. They will darken, but the flavour survives well enough for curries. You can also blitz leaves with a little oil and freeze in ice-cube trays — a useful trick when a recipe needs just a spoonful.

Growing your own is genuinely worthwhile. All three basils like warmth, sunshine and regular watering, and pinching out the tips encourages bushy growth. Keep them away from cold draughts and harvest little and often. A pot of holy basil by the kitchen window will pay for itself in a single summer of stir-fries.

Matching Basil to Dish

The simplest rule is this: holy basil for heat and stir-fries, Thai basil for curries, salads and noodles, sweet basil for gentle coconut dishes and garnishes. When in doubt, taste a leaf raw and let your own palate decide. Thai cooking is far more forgiving than its reputation suggests, and the pleasure of getting the right basil in the right pan is one of the small, satisfying discoveries of home cooking.