Place shrimp paste on a small piece of foil and then fold the foil up to form a packet that completely encloses the shrimp paste.
Heat a skillet over medium-high heat. Place shrimp paste packet onto heated skillet and toast for about 2 to 3 minutes on each side, until fragrant. Set aside.
Return skillet to medium-high heat and add coriander seeds, cumin seeds and white peppercorn. Toast spices, stirring constantly, until fragrant, 4 to 5 minutes.
Grind coriander seeds, cumin seeds, and white peppercorn using a mortar and pestle or spice grinder until they form a fine powder. Set ground spices aside. (Note: if you don’t have a mortar and pestle or a dedicated spice grinder, you can also pulse the dried spices in the blender or food processor, but it may take up to 10 minutes of blending / pulsing until a fine powder forms.)
If using a mortar and pestle:Using a mortar and pestle, grind lemongrass, galangal, and salt until smooth. Add shallots, garlic, lime peel, and cilantro root. Grind again until smooth.Add chili peppers and grind once more until smooth.Add shrimp paste and dried spices. Continue to grind / mix everything together until even. If using a blender or food processor:In a blender or food processor, combine lemongrass, galangal, shallots, garlic, lime peel, cilantro root, chili peppers, and shrimp paste. Blend until the mixture forms a paste that still has a small amount of texture, pausing to scrape down the sides as needed. (Note: if the mixture does not blend easily, add water a bit at a time, as needed, to help it blend.)Add dried spices and salt and blend just until the spices are fully mixed in.
Taste curry paste and season with some additional salt, if needed.
Curry paste can be stored in the refrigerator for about 1 week or frozen for up to a year.