Place the chilli powder, ground coriander, cumin, garlic, onion, lemon grass, galangal or ginger, palm sugar, shrimp paste, peanuts and coconut milk in a food processor and process until fairly smooth.
Place a large wok over a high heat and add the spice mixture. Bring to the boil, reduce the heat and simmer gently, uncovered, for 12–15 minutes, stirring occasionally.
Add the green beans, prawns and scallops and bring back to the boil. Reduce the heat and simmer gently for 6–8 minutes or until the prawns and scallops are cooked through.
Remove from the heat and scatter over some Thai basil leaves, chopped roasted peanuts and sliced red chilli before serving.