The Thai granite mortar (ครกหิน, khrok hin) is a large, heavy mortar used for pounding curry pastes and making som tam. Granite’s roughness grips spice particles and plant fibres, enabling grinding that a smooth marble mortar cannot achieve.
Size matters
A Thai mortar used for curry paste should be at least 20 cm diameter with a bowl depth of at least 10 cm. A small decorative mortar cannot hold the volume of aromatics needed for a full batch of curry paste without spraying ingredients over the rim during pounding.
Pounding vs grinding
Thai mortar technique is pounding with a downward motion, not circular grinding. This bruises plant fibres and releases volatile oils without generating the heat that circular grinding can produce. For curry paste: pound each dry ingredient individually, then combine and pound together.