Heat the oil in a frying pan. Add the onion and garlic and fry for 2–3 minutes until softened. Add the rice and cook for a further minute, making sure that the rice is coated in the oil. Add the wine and cook for a further minute, and then gradually add the stock, ladle by ladle, stirring continuously and allowing each addition of stock to be absorbed before adding the next.
Add the prawns and peas with the final ladleful of stock and add the lemon rind and juice. Stir until the prawns and peas are cooked and heated through. Remove the pan from the heat and stir through the butter, Parmesan and parsley. Season to taste with salt and pepper and serve.