To make the pesto, toast the nuts in a small dry frying pan for 2-3 minutes until lightly golden and smelling toasted. Tip onto a plate and cool for a minute. Transfer to a food processor with the salad leaves, herbs, cheese, garlic and oil, and pulse a few times to combine. Scrape down the sides, then blend again until you get a chunky pesto, or continue blending if you prefer a smoother pesto. Season well, adding enough just enough of the lemon juice to balance any bitterness from the salad leaves. The pesto will keep in an airtight container in the fridge for four to five days.