1. Grind all spice mixture ingredients in a mortar and pound until mixed thoroughly (or using food processor).
2. Heat vegetable stock or water in a pot, then add spice mixture and keep stirring it.
3. When the soup boils again, add fish sauce. Wait for another 20 seconds, then add prawns, vegetables.
4. When vegetables are cooked thoroughly, taste and add fish sauce or salt as desired, then remove from heat.
5. Transfer to a serving bowl and serve immediately with hot steamed rice.
(For 2 Serving)