Add non-dairy milk, dates, mint leaves, chia powder, matcha powder and salt to a Vitamix or other high speed blender, and process until smooth (when you can no longer see pieces of mint leaves or dates).
Pour the pudding into a container (or divide into 4 serving dishes), and refrigerate overnight or for at least 5 hours.
Notes
6-7 dates will give you a sweeter pudding, but will start to turn the color green-brown. Sub ¼ cup (or more) of maple syrup or another light-colored sweetener if you want to keep the pale green color.
You can buy pre-ground chia seeds, or grind up whole seeds right in the blender.
Japanese tea has a lower lead content than Chinese tea. See this video for more details.