Combine the black and white rices and rinse in a bowl to remove most of the starch. Place the rice, pandan leaves, salt and water in a heavy pot. Bring to the boil and simmer.
Grate the palm sugar and add to the water. Simmer until the sugar dissolves (about 5 minutes).
When the rice has been cooking 30 minutes, add the syrup and cook another 10 minutes.