Toast cumin seeds by adding them to a dry sauté pan and stir constantly over medium-high heat until the seeds are aromatic and slightly darkened, about 4 minutes. Cool on a plate. Repeat with the coriander seeds.
1 teaspoon cumin seeds, 2 teaspoons coriander seeds
Using a mortar and pestle, grind toasted coriander seeds, toasted cumin seeds, and white peppercorns into a fine powder. Remove from mortar and set aside.
½ teaspoon white peppercorns
Cut at least 8 green Thai chilies in half horizontally and, with a paring knife, scrape off and discard the seeds and pith, then finely chop along with the remaining chilies.Note: The seeds and pith are removed from some of the chilies to tone down the heat, you can remove seeds from all of the green chilies if you wish to tone it down even more 15 green Thai chilies
Add chopped chilies and salt to a heavy-duty mortar and pestle; pound into a fine paste. If the mixture feels too wet at any point, add some of the ground spices to absorb the liquid.
1 teaspoon coarse salt
Add basil leaves; pound into a fine paste.
15 Thai basil leaves
Add lemongrass, galangal, makrut lime zest, and cilantro roots; pound into a fine paste.
3 Tablespoons thinly sliced lemongrass, 1 Tablespoon finely chopped galangal, 2 teaspoons makrut lime zest, 2 cilantro roots or 4 big cilantro stems
Add shallots, garlic, and any remaining ground spices; pound into a fine paste.
3 Tablespoons finely chopped shallots, 2 Tablespoons finely chopped garlic
Add shrimp paste and pound to mix.
1 teaspoon fermented shrimp paste (gapi)