In a dry pan, combine coriander seeds, cumin seeds, coarse sea salt and white peppercorns and cook over moderate heat for 2 to 3 minutes. Place the spices in a mortar and finely grind or use a food processor and blend until smooth. Add dried finger chilli peppers, lemongrass, shallots, garlic cloves, galangal, lime zest and kaffir lime leaves and finely grind.