We like that this green smoothie is sweet but not cloyingly so. Apple juice gets the blender moving and banana acts to emulsify the kale and celery. This smoothie is best made in a high powered blender, but if you have a standard model here are some tips to help you puree to perfection. Remove the kale stems and tear the leaves into bite-size pieces. This will help prevent them from getting stuck around the blade. Chop the celery and banana into ½-inch pieces and really let ‘er rip for a minute or 2. Scrape down the sides of the blender as necessary and blend again for a straw-friendly sipper.