Thai basil is one of many basil varieties. Sweet basil is well known for its inclusion in many Mediterranean dishes while Thai basil plays an equally important role in Thai cuisine. Consider its use in dishes like pad ki mao (drunken noodles) and green curry. Thai basil is as important to the flavor of Thai food as fish sauce and kaffir lime leaves. This means that if you plan to cook Thai food, you should try to get some of this herb to get an authentic flavor. If you are unable to find Thai basil, you can use one of the substitutes below.
Sweet basil a.k.a. Italian basil
This Mediterranean herb is arguably the most popular herb in the western world and is used for everything from Italian marinara sauces to pesto. It also belongs to the same family as Thai basil and thus shares much of the flavor and nutritional value. You can use sweet basil in all dishes that require Thai basil without losing much. In fact, it may be able to provide some additional depth and complexity due to its herbal notes. Note that one of Thai basil’s defining characteristics is its intensity. It is sweeter and more pungent than the sweet variety.
When using sweet basil in place of Thai basil, you may be able to replicate this intensity by using a little more of the herb than your recipe requires for Thai basil. Try using about one and a half times more sweet basil. Note that sweet basil does not handle cooking as well as Thai basil, so you may want to add it closer to the end of cooking time.
Holy basil a.k.a. tulsi
Many Indians consider holy basil to be a sacred herb, but it is also quite popular in Thailand. Thai dishes that include holy basil include gai pad krapow (chicken and holy basil). Note that Thai cooks use holy basil for its spiciness, not for its sweetness; in fact, they refer to it as “hot basil” to distinguish it from Thai basil. If you need the sweetness of Thai basil, consider combining holy basil with some sweet basil. If you decide to use holy basil as your Thai basil substitute, use the same amount that your recipe requires for the Thai herb.
Star anise is different from anise seed, though the two do share many flavor notes in common; in particular, they share licorice notes. Those licorice notes are what you want from Thai basil. Star anise comes from an evergreen tree native to parts of Vietnam and China. This spice is very pungent when it is packaged and stored correctly; you need only a little to add a lot of its flavor to your dish. Start by adding a single petal or half a teaspoon of the ground spice and increase to taste.
Tarragon is a herb that can be used to replicate the licorice notes in Thai basil. It is popular in French cooking as a way to flavor poultry and fish and is one of the fines herbes. Start by adding half the amount that your recipe requires for Thai basil and increase if necessary.
Fennel is another herb known for its licorice flavor. You can use the leaves of this plant as a herb and the bulb part as a vegetable in salads and cooked dishes. When used in place of Thai basil, the fennel herb can provide an intense licorice sweetness. Note that the flavor is somewhat less pungent than that of Thai basil, so start by using one and a half times the amount that your recipe requires for Thai basil.