Put the chopped rocket, the freshly grated Parmesan cheese, the toasted walnuts and the crushed cloves of garlic into a food processor. Whizz up, then add the extra-virgin olive oil in a steady stream, along with a good pinch of the salt. Taste, and add more salt if necessary, then pour in to a jar and cover with ½cm (¼in) of the olive oil. Cover and put in the fridge, where it will keep for a couple of weeks.

Rocket Recipes: 

• Rocket and walnut pesto
• Rocket and Feta salad
• Rocket, pear and blue cheese salad
• Beef carpaccio with rocket
• Rocket, goat's cheese and honey bruschetta
• Smoked mackerel, apple and fennel salad