I found the celery taste a little strong though, even after adding a few drops of stevia, but the granny smith apples gave it some punch! This was the first green smoothie I have made with banana that was not overpowered by just that flavor.
1 Banana, Peel and chope up a bit
1 Granny Smith Apple, Core and chope up (leave skin on)
1 Hand full of spinach
1 Stalk of celery, cut up into a few pieces
1 cup Water or your favorite mylk
Throw it all in a blender and put in the water or mylk (or both) to get it going. Serve as is or chill for better taste (in my opinion).