Heat the oil in a large frying pan. Fry the onion, garlic and half the chilli for 5 mins or until softened. Add the curry paste and cook for 1 min more. Add the tomato purée, stock and coconut cream.
Simmer on medium heat for 10 mins, then add the prawns. Cook for 3 mins or until they turn opaque. Scatter on the remaining green chillies and coriander sprigs, then serve with rice or cauliflower rice for a keto-friendly version.