Into a large frying pan, spray some low calorie cooking spray and fry the onion and garlic on a low heat until translucent (for around 5 minutes).
Add the risotto rice to the pan and stir to incorporate the onions and garlic. Add in the chopped tomatoes, herbs, tomato puree and stock stirring well to mix. Leave to simmer for 10 minutes, stirring occasionally.
Add the prawns, asparagus and courgette and cook for a further 10 minutes, stirring occasionally, until the liquid has been absorbed. If the rice starts to stick to the bottom, add a little more stock to loosen.
The rice is ready when it feels tender and should be served a little al dente. Serve immediately and dust with a tiny sprinkle of parmesan.