For the green curry paste, lightly roast the coriander and cumin seeds and the peppercorns in a dry heavy-based frying pan, then grind to a powder in a coffee or spice grinder. Pound the chillies, lemongrass, galangal, shallots, garlic, coriander roots, turmeric, lime zest and shrimp paste in a mortar with a pestle.
Pass all the ground and pounded ingredients through a mincer twice, or use a blender to process until smooth, adding a little water or oil if necessary. You can also just keep pounding with the pestle to produce a fine paste. Set aside 130 g (4¾ oz/about ½ cup) of paste for the curry. (Any leftover paste will freeze until next time.)
To make the curry, place the coconut cream and oil in a heavy-based frying pan over high heat and bring to the boil, stirring continuously. When the coconut cream splits (the oil and solids separate), add the curry paste. Crush the lime leaves in your hand, add them to the pan and fry for 10–15 minutes or until the mixture is sizzling and aromatic (use your nose).
Add the fish sauce and cook for 1 minute. Add the palm sugar and coconut milk and bring to the boil. Add the prawns, chillies and eggplants and simmer gently for 4 minutes or until the prawns are just cooked and the pea and apple eggplants are still a little crunchy. Stir in the basil just before serving.