Start by making the pea stock. In a large pan of simmering water, blanch the pea pod shells for 1 minute. Using a slotted spoon, remove the blanched shells and refresh them in the iced water. (This keeps the colour and freshness.)
Once cooled, blend the iced water and pea pods in a food processor until smooth. Strain through a fine sieve. Set aside 100ml/3½fl oz to make the pea purée and the remaining 500ml/18fl oz to make the risotto. (Add water to make the volume up to 500ml/18fl oz if necessary.)
For the pea purée. In a small saucepan on a medium heat, cook the peas in the butter for 5 minutes, adding a pinch of salt. Add the 100ml/3½fl oz reserved pea stock, bring to a boil and simmer for 4 minutes. Transfer to a blender or food processor, blend until smooth and leave to cool.
For the risotto, in a medium saucepan on a low heat, gently fry the onion in the olive oil with a pinch of salt for 2 minutes, until translucent. Add the garlic. Stir in the rice and continue to cook for 3 minutes, until the grains appear shiny (this will give flavour and prevent them sticking together).
Pour in the wine, then 500ml/18fl oz reserved pea stock, stir and bring to the gentlest simmer with only one bubble breaking the surface every minute. Season with salt and pepper then cover with a lid and cook for 20 minutes. Check every now and again that it is not boiling.
After 20 minutes examine a grain of rice and check for a tiny speck of white starch in the middle. This means the risotto is nearly cooked. Stir the rice quickly for 5 minutes to achieve a creamy consistency.
Stir in 200ml/7fl oz cooled pea purée and the Parmesan. Season to taste and set aside.
For the vegetables, in a small saucepan on a high heat, bring the butter, 50ml/2fl oz water and a pinch of salt to the boil. Add the courgettes, cover with a lid and cook on a high heat for 30 seconds, then add the peas, radishes, radish tops and spinach, cover again and cook for 20 seconds. Drain and set aside.
To finish the risotto, stir in the lemon juice and olive oil. Taste and adjust the seasoning. Add a dash of white wine to sharpen the flavour if desired.
Serve the risotto in a large dish topped with the vegetables, blanched pea shoots and a few shavings of Parmesan.