1. To make the green herb sauce,whiz the spinach leaves in a food processor with the parsley,basil,chives,garlic and lemon zest. Add 125ml (½ cup) of the stock,season with salt and pepper and pulse until smooth. Set aside.
2. In a saucepan,bring the remaining stock to the boil,then keep at a very low simmer.
3. Melt 1 tbsp butter and olive oil in a heavy-bottomed saucepan or pot,add the onion and cook over low heat for 3 minutes until it softens,stirring constantly with a wooden spoon. Add the unwashed rice,and cook for 3 minutes,stirring constantly until well-coated.
4. Add the wine all at once,and let it bubble away,stirring. When absorbed,increase heat to medium and add a ladleful (half a cup) of the hot stock,stirring constantly.
5. When the rice has absorbed the stock,add another ladleful,stirring serenely. Continue this process until all the stock is absorbed. It will take about 15 minutes until the rice is tender and creamy,with just a tiny,white pinhead of starch inside.
6. Beat in the herb sauce,extra 1 tbsp cold butter and parmesan,and taste for salt and pepper. The rice should be thick but move slowly when you tip the plate. Top with a grating of parmesan and extra herbs. To make the dish more substantial,you can add a fried or poached egg.
Tip:The rice is ready for another ladleful of broth when your wooden spoon can draw a stripe through the risotto on the base of the pan,like the biblical parting of the sea.