Heat the oil in a frying pan, add the onion and fry until translucent. Add the garlic and risotto rice and fry for 2 minutes, stirring to coat the rice with the oil. Pour in the wine and leave to bubble until just 1 tablespoon of liquid is left.
Add the stock over a medium heat, a ladleful at a time, stirring continuously. Allow each ladleful of stock to be absorbed before adding the next. Keep adding stock until the rice is cooked but still has a slight bite to it. This should take about 15–20 minutes.
Add the prawns and courgettes just before the last couple of ladles of stock go in. Cook until the prawns are pink and firm to the touch, about 3 minutes. Finally, stir in the peas, butter, mint and lemon rind. Season to taste with salt, pepper and lemon juice.