Green pastes tend to be a bit more pungent than their red cousins simply because chilies sweeten somewhat as they ripen and become red.
3 tablespoons coriander seeds, toasted
2 teaspoons cumin seeds, toasted
6–8 red serrano chilies, seeded and chopped
1 medium onion, chopped
2 garlic cloves, chopped
1 stalk lemongrass, outer leaves removed and discarded, inner core finely chopped
1 (½-inch) piece ginger, finely chopped
3 kaffir lime leaves or the peel of 1 lime, chopped
2 teaspoons paprika
4 tablespoons water
2 tablespoons Tamarind Concentrate (see recipe on page 18)
3 tablespoons vegetable oil
1 teaspoon salt