First make the pesto. Put the olive oil and lemon juice in a blender, add the basil, rocket, garlic, nuts, cayenne pepper, date and avocado and blend well. Scrape down the sides of the blender and blend again, until smooth and creamy. Season and add a little more olive oil or a few drops of water if the mixture seems too thick. The pesto can be stored in an airtight container in the fridge for 2-3 days.