Begin by preparing the Thai sticky rice. Pour hot water (90-100℃) over the rice, ensuring the water level is approximately 3 cm above the rice. Allow the rice to soak for 1 hour.

For the filling, place the sweet potato in a bowl and pour in the water. Microwave the mixture at 600W for 7 minutes and 30 seconds. Once cooked, drain the sweet potato thoroughly. Mash the sweet potato using a hand mixer until smooth. Add the coconut milk and sugar, then beat until fully incorporated. Transfer the sweet potato filling to a piping bag for ease of use.

Drain the soaked rice and place it in a microwave-safe bowl. Pour the water over the rice, cover the bowl, and heat it in the microwave at 600W for 10 minutes.

In a separate bowl, mix the coconut milk with sugar and salt, then microwave this mixture at 600W for 40 seconds. Remove the rice from the microwave and immediately pour the warmed coconut milk mixture over it. Stir to combine, ensuring the rice is evenly coated. Cover the bowl and let the mixture rest for 10 minutes to absorb the flavors.

To assemble, spoon a portion of the coconut sticky rice onto a piece of banana leaf. Pipe a line of the sweet potato filling over the rice. Wrap the banana leaf tightly around the rice and filling, ensuring a snug fit. Place the wrapped rice on another banana leaf and wrap it tightly again. Secure the package with toothpicks and trim any excess banana leaf with scissors for a neat presentation.

Preheat a griller and place the wrapped sticky rice parcels onto the grill. Cook until the banana leaf is charred, imparting a smoky aroma to the dish.

Serve warm and enjoy the delightful combination of sweet potato filling and coconut sticky rice encased in aromatic banana leaf.