Steam sweet potatoes until they are soft.

Combine the steamed sweet potatoes and coconut milk in a blender.

Blend until smooth.

Strain the mixture through a fine sieve to remove any lumps.

In a saucepan, combine agar-agar powder, sugar, water, and knotted screwpine leaves (or pandan extract).

Bring the mixture to a boil, stirring until the agar-agar dissolves completely.

Stir in the pureed sweet potato and coconut milk mixture into the saucepan.

Simmer over low heat, stirring continuously.

Add a pinch of salt.

Pour the jelly mixture into a wet tray or mold.

Let it set at room temperature.

Chill well in the refrigerator before cutting into desired shapes and serving.