Step 1

Toast coriander and cumin seeds with the pepper in a wok or pan over medium heat for 1-2 minutes until fragrant, shaking pan to prevent burning. Cool slightly. Grind to a fine powder using a mortar and pestle.

Step 2

Wrap shrimp paste in a square of foil. Dry-fry in a wok or pan over medium heat for 1 minute each side to toast slightly. Cool, then add to mortar with remaining ingredients and pound with pestle until roughly crushed. Add 1 tablespoon water and use a stick blender (or transfer to a processor) to blend to a paste. Store in an airtight container in the fridge for up to 2 weeks.