Cut the sweet potato in in eight pieces and put to boil. Test with an ice pick or knife. It should go through smoothly when ready. Drain and leave to cool.
Grate using the large side of the grater. Blend in 2 cups of water; then sweeten with the condensed milk, evaporated milk and vanilla essence. You may also add sugar to taste as well.
Note: If you find the punch too thick, adjust milk and sugar to taste. Strain to remove excess fiber.
Serve with ice.