If you are so lucky as to have a kumquat tree (or live near one that you can discretely pillage), definitely try the kumquat. It really adds something here. Otherwise, a clementine orange will do the trick.
1 cup of flaxseed milk
pinch of sea salt
few drops of vanilla extract
1 head of organic baby bok choy
1 very ripe banana
1 round kumquat, peel and all
1 cup of frozen wild blueberries
Blend all and drink up!