Rim a tall glass with tajin. In a blender, blend the mango, water/coconut milk, lime juice, and a handful of ice together until smooth. Add more ice as desired. Spoon the mango smoothie into the prepared glass, then layer the smoothie with the chamoy sauce, working your way up the glass and finishing with the chamoy sauce. Then top with fresh mango and tajin. Add a tamarind stick if desired. Enjoy!