Why It Works
- Thinly slicing the fresh aromatics makes them easier to pound into a paste in the mortar and pestle.
- A mixture of mild serrano and spicy Thai chiles lends the paste fruity and fiery notes, and bright pale green color.
For many Americans, green curry, or gaeng khiao waan, has become synonymous with Thai cuisine, so much so that if a Thai restaurant didn’t have a green curry prominently featured on the menu, most people would eye the kitchen with suspicion. Likewise, if you’re a fan of Thai food and you like cooking, you probably have a can of green curry paste in your pantry right now, or know where you can find some easily, since prepared Thai curry pastes are quite easy to find at well-stocked grocery stores, Asian markets, and, of course, online.
The fact that green curry and prepared green curry pastes are easy to find might make you think there’s no reason to make green curry paste from scratch at home. However, I think that because green curry is so familiar to so many, making your own green curry paste, or prik gaeng khiao waan, can clearly illustrate why and how scratch-made curry pastes are superior to prepared versions, provided you prepare them with an eye toward proper technique and seasoning. A freshly made prik gaeng is intensely aromatic because of the pounded ingredients, and you’re able to easily pick out each component—the fruitiness and pungency of fresh chiles and alliums, the floral and herbal notes of lemongrass and galangal, the heady depth of ground spices, and the savory punch of shrimp paste. A canned curry paste doesn't have any of the brightness and nuance of a fresh paste, and the flavors of each component are muted and muddy in comparison. Making green curry paste also offers a few lessons in ingredient substitution, and necessitates careful consideration of how and in what order you combine ingredients in a mortar and pestle.
The main ingredients for prik gaeng khiao waan are relatively easy to find and frequently used in a wide variety of curry pastes: chiles, lemongrass, galangal, makrut lime zest, coriander root, garlic, shallots, dried spices, and shrimp paste. For example, the only difference between a green curry paste and a basic red curry paste (prik gaeng phet) is the color of the chiles used (red curry paste is made with dried red chiles rather than fresh green ones).
In Thailand, green curry paste is made with a variety of green chiles, the most common being prik kee noo suan khiao, a small, spicy green chile that's hard to source in the US; prik cheefa khiao, a large, green spur chile that sits on the milder side of the heat index spectrum; and prik jinda khiao, the skinnier, smaller, spicy green peppers known in the US as “Thai chiles.” The combination provides a balance between the fruity and the fiery notes of fresh chiles, while also lending the paste its distinctive pale green hue.
Making a green curry paste in the US requires that you get a little creative with chile substitution, since many varieties of fresh Thai chiles can be hard to find. Serrano chiles work well as a like-for-like substitution for spur chiles, but if you have access to a Korean market, such as HMart, I’ve also had success using a combination of mild (asagi gochu) and spicy (cheong-yang gochu) Korean green chiles. The goal with any chile substitution is to provide the paste with its color, the fruity aroma and flavor of a fresh pepper, and to ensure that the chile paste is sufficiently but not overpoweringly spicy.
The high moisture content of fresh chiles makes green curry paste one of the trickiest Thai curry pastes to pound by hand in a mortar and pestle. As the chiles break down in the mortar they release water, which makes it harder to generate the abrasive friction between the pestle and mortar that’s required to pound the more fibrous ingredients into a fine paste.
There are a few tricks and tips that can make this process easier. The first is to make sure the ground spices and salt in the recipe are already in the mortar when you start pounding the chiles so they can absorb some of the liquid; it’s common with other curry paste preparations to add them later. I also recommend that in the initial stages of pounding the fresh chiles you keep the pestle as close as possible to the ingredients while pounding, so you don’t have chile juice and shrapnel splashing in your eyes (trust me, it isn’t pleasant).
Once the chiles are broken down into a paste, you can start lifting the pestle higher to pound with more force from a greater height, although you should make sure to use the sides of the mortar to help break down ingredients—while pounding in the center of the bowl is definitely called for, it is the friction created by the pestle rubbing against the mortar’s walls that does most of the work in breaking up the ingredients. Finally, thinly slicing the aromatics that go into the paste—particularly fibrous galangal and lemongrass—significantly speeds up the process. The ingredients have to get broken down at some point, and taking the time to (carefully) slice them beforehand will save you a lot of time and effort.
This recipe produces roughly four ounces (1/2 cup) of curry paste, which is the equivalent of one can of store-bought paste. I decided on this quantity because if you want to make green curry using my green curry recipe but don’t feel like making curry paste from scratch, you can easily substitute a store-bought paste. But the relatively small quantity of paste this recipe produces means that it can’t be made easily in a standard-sized food processor or blender: The volume of ingredients is too small to be processed properly, and much of it will just get stuck to the sides of the blender jar or processor bowl without getting pulverized.
However, if you want to scale up the recipe to make a much larger batch of paste, the high moisture content of the chiles will work to your advantage, as it makes it easy to purée the ingredients in a blender. The paste can then be divided into four-ounce portions and frozen for months. That said, I do recommend making this recipe in a mortar and pestle to get a feel for the process and the desired texture of the paste. With a little practice, pounding a curry paste doesn’t take all that much effort, especially if you follow some basic technique principles.
- Make sure to thinly slice the fresh aromatics before adding them to the mortar; smaller pieces are much easier to process into a paste.
- Add only one ingredient at a time to the mortar (because of the small quantities and comparable texture, shallots and garlic can be added at the same time), and don't move on to the next one until you have fully pulverized the latest addition; overcrowding the mortar will just slow you down and make a mess.
- Use the weight of the pestle to your advantage; start by simply tapping the ingredients with the heavy pestle to crush them, and then move on to more energetic pounding.
- Embrace the process; once you get the paste going, it becomes easier to incorporate each subsequent ingredient.
- Give yourself some arm relief by grinding whole spices separately in a spice grinder before incorporating them into the paste in the mortar and pestle.
- 3 Thai or Chinese white cardamom pods (see note)
- 1 teaspoon whole coriander seeds
- 1/4 teaspoon whole cumin seeds
- 1/2 teaspoon white peppercorns
- 1/2 teaspoon Diamond Crystal kosher salt
- 3 fresh serrano chiles (40g), stemmed and thinly sliced
- 15 fresh green Thai chiles (15g), stemmed
- Peeled zest of 1 makrut lime (3g) (optional, see note)
- 3 coriander roots (10g), cleaned (see note)
- One 2-inch piece fresh galangal, peeled and thinly sliced (about 2 tablespoons; 15g) (see note)
- 2 stalks lemongrass, bottom 4 to 5 inches only, outer leaves discarded, tender core thinly sliced (about 20g sliced lemongrass)
- 3 small garlic cloves (10g), thinly sliced
- 1 small shallot (20g), thinly sliced
- 1/2 teaspoon (5g) Thai shrimp paste
In a small skillet, combine cardamom, coriander, and cumin, and toast over medium-low heat, swirling and tossing frequently, until fragrant, 2 to 3 minutes. Transfer spices to a granite mortar and pestle or spice grinder along with white peppercorns and salt. Allow to cool slightly, and peel and discard husks from cardamom pods. Grind to a fine powder. If using a spice grinder, transfer mixture to a granite mortar and pestle.
Add half the serrano chiles to the mortar and pound until slightly broken down, making sure to keep the pestle as close to the chiles as possible to avoid splattering chile juices over yourself. Add remaining serrano chiles and pound to a coarse paste, about 3 minutes.
Pounding thoroughly between each addition to break down and incorporate ingredients into the paste (3 to 4 minutes of pounding per addition) add in the following order: Thai chiles; makrut lime zest (if using); galangal; lemongrass; coriander root; shallots and garlic; and shrimp paste. It should take about 25 minutes total to pound ingredients into a very fine paste. Use right away or transfer curry paste to an airtight container, covering paste with plastic wrap pressed directly onto its surface to prevent it from drying out, and refrigerate for up to 1 week or freeze for up to 3 months.
Thai or Chinese white cardamom can be found in Southeast and East Asian markets or online. Its flavor is both more floral and subdued than green cardamom's.
Galangal is a rhizome and an integral part of basic red curry pastes. If you are in the US, it's usually best to peel it before slicing as most of what we get is mature galangal, which is very tough to work with. While galangal looks like ginger, they are not interchangeable, as their flavors are very different.
Fresh makrut limes can be hard to find in the US. You can order them online, though they are a seasonal product and may not always be available (note that they are often sold under a different name that we avoid using, as it is a derogatory term in some contexts); you may also be able to find them in the freezer section at Southeast Asian markets. Makrut lime zest freezes well. If you cannot find makrut lime, you are better off omitting it, as the more common Persian lime and other citrus are not good substitutes.
The roots of fresh coriander (a.k.a. cilantro) provide a slight herbal note to curry pastes, but unfortunately they're hard to find in the US, as they are often cut off from the stems before cilantro is brought to market (though local farmers markets in the summer and fall often have coriander with the roots still attached). Coriander roots can be found at Southeast Asian markets. If you can't find the herb with the roots still attached, you can either use the tender stems of fresh cilantro, which won't make too much of a difference in this particular curry, or omit it altogether. And, to clarify, although they are called coriander "roots," Thai cooks usually also use some of the tender green stem.
Make-Ahead and Storage
Curry paste can be refrigerated in an airtight container, with plastic wrap pressed directly against the surface of the paste to prevent it from drying out, for up to 1 week, or frozen for up to 3 months.