Steaming method: Place sweet potatoes in a steamer, sprinkle with some sugar on top and steam for about 8 to 10 minutes until cooked.
Boiling method: Fill a saucepan with water, add 1 screwpine leaf and bring to the boil. Add yam and sweet potato. Simmer till cooked, but not mushy. Remove the yam and sweet potato with a slotted spoon, leave to cool.
In a pot, boil water along with the remaining pandan leaves. Add sago and cook till translucent. Once cooked, strain the sago.
In a large pot, melt gula melaka with 1 cup of the water. If there are impurities in your syrup, strain it. Add the sweet potatoes, yam and gula melaka. Boil for 5 minutes.
Finally add the coconut milk, cooked sago and salt.
If you desire a sweeter soup, add some white or brown sugar. Let all the ingredients simmer for about 5 more minutes and it is ready to be served hot. If you prefer it to be cool, let it cool to room temperature and chill it for a couple of hours.