Soaking the cashews ahead of time will help make the cashews more easily digestible and will lend itself to that velvety texture you're looking for here. If you don't have a high speed blender, you can still make this smoothie. You'll just need to be patient, and scrape down the sides of your blender regularly. If you do have a high speed blender, you don't *have* to soak the cashews, but I still recommend it if you have time.