Notes:
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.
by Derek Lucci
Updated Jul. 12, 2021
"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."
"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."
"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.
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