Step 1

Place stock in a saucepan and bring to the boil. Reduce heat to low and keep at a gentle simmer.

Step 2

Heat oil and butter in a heavy-based saucepan over medium heat. Add onions and cook, stirring, for 5 minutes or until translucent. Add rice and cook, stirring, for 2 minutes or until well coated in mixture. Gradually add 250ml (1 cup) stock, stirring occasionally, until stock is absorbed. Repeat until all stock is used and rice is al dente; this will take about 20 minutes.

Step 3

Stir basil, asparagus, parmesan and lemon zest into risotto. Remove from heat and stand for 5 minutes; the residual heat will cook asparagus. Season with salt and pepper.

Step 4

Divide the risotto among bowls. Scatter with extra basil and shaved parmesan to serve.