Step 1: In a medium saucepan, whisk together the rice flour, salt, and 2 cups of water until completely smooth and lump-free. This creates the base for your Indonesian Sweet Coconut Rice Pudding (Bubur Sumsum).
Step 2: Pour in the two cans of full-fat coconut milk. Add the knotted pandan leaf (if using) to the mixture. Stir well to combine all ingredients.
Step 3: Place the saucepan over medium heat. Begin stirring the mixture continuously with a whisk or wooden spoon. It’s crucial to stir constantly to prevent lumps from forming and to ensure even cooking.
Step 4: Continue stirring for approximately 10-15 minutes. The mixture will gradually thicken and become glossy. Keep stirring until it reaches a thick, pudding-like consistency that coats the back of your spoon and gently bubbles.
Step 5: Once thickened, remove the saucepan from the heat and discard the pandan leaf. Ladle the hot Indonesian Sweet Coconut Rice Pudding (Bubur Sumsum) into individual serving bowls. Set aside to cool slightly while you prepare the syrup.
Step 6: To make the palm sugar syrup, combine the grated palm sugar, 1/2 cup water, and the second knotted pandan leaf (if using) in a small saucepan.
Step 7: Bring the syrup mixture to a simmer over medium heat, stirring occasionally until the palm sugar has completely dissolved and the syrup is smooth and slightly thickened.
Step 8: Remove the syrup from the heat and discard the pandan leaf. Strain the syrup through a fine-mesh sieve into a clean bowl or jug to remove any impurities.
Step 9: To serve, drizzle a generous amount of the warm palm sugar syrup over each bowl of Indonesian Sweet Coconut Rice Pudding (Bubur Sumsum). Enjoy warm or chilled.