Heat the oil and butter in a heavy-based saucepan, add the onion and cook over a medium heat for 2–3 minutes until softened. Stir in the garlic and curry paste and cook for a further 1–2 minutes until fragrant, then add the rice and stir to coat well.
Stir in the stock, peas and lime rind, then season well and bring to the boil. Cover tightly, then reduce the heat to low and cook for 12–15 minutes or until the liquid is absorbed and the rice is tender.
Remove the pan from the heat, then stir in the lime juice, coriander and prawns. Cover and leave the prawns to heat through for a few minutes before serving.