Step 1

Place spur chiles in a small heat-resistant bowl and add enough hot water to cover. Steep until softened, 10 to 15 minutes. Transfer rehydrated chiles to a granite mortar and pestle and pound until pulverized, 3 to 5 minutes.

Step 2

Pounding thoroughly between each addition to break down and incorporate each ingredient into the paste, add lemongrass, galangal, makrut lime zest (if using), coriander roots (if using), garlic, shallot, shrimp paste, peanuts, nutmeg, coriander seeds, cumin seeds, and white peppercorns until a very fine paste forms, about 25 minutes. 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.