Heat the butter in a large saucepan and when it is bubbling, add the onion and cook over a medium heat for 5 minutes.
Add the rice and stir it around so it is well coated in the butter. Fry for 2 minutes. Pour in the wine or vermouth and stir until it has all evaporated. The alcohol will evaporate off but you can skip the wine if you prefer.
Pour in the stock and season with salt and black pepper then stir in the prawns and peas.
Bring the pan to simmer then cover with a tight fitting lid and turn the heat down low. Cook for 15 - 20 minutes until the rice is softened, stirring occasionally.
When the rice is cooked, stir in the lemon juice, half the zest and the parmesan. Let it rest for 2 - 5 minutes to allow it to go creamy.
Serve with the parsley and lemon zest sprinkled over the top.
Arborio rice is the best rice for making a risotto. You can use other short grain rice varieties but avoid long grain varieties such as basmati and jasmine as you won't get the creamy texture. Don't rinse the arborio rice before cooking as the startch gives it the creamy texture.
Cooked King Prawns are the best for this recipe but you can use smaller prawns of shrimps if you prefer.
You can safely and quickly defrost prawns in a bowl of cold water. It will take 10 - 15 minutes.
If you don't have fresh lemons you can use bottled lemon juice to add a lemon flavour.
Use a vegetable or fish stock. The salt content of stocks can vary so check before adding your seasoning.
A risotto is best eaten as soon as it is cooked. You can store this prawn and pea risotto in the fridge for just 1 -2 days. Make sure when you reheat it that it is piping hot. You may also need to add a little extra stock to loosen it. A risotto doesn't freeze well as the texture of the rice goes hard and grainy.