Rinse the rice until water is clear and then set aside.
In a large saucepan or large wok, add the coconut milk, ginger is and bring the mixture to a boil, then reduce to a simmer. Stir continuously until milk solids separate from the coconut milk.
Next, add water, sugar, salt and bring to a quick boil and then reduce to a simmer for 3 minutes.
Add the rice and continue mixing on low heat until the water has been absorbed, about 10 minutes. Remove from heat and allow to slightly cool.
Measure out about 80 grams of the rice mixture and place on the banana leaf, and roll into logs. Roll banana leaves tightly around the rice to form a log and fold both edges to seal. Repeat the steps until all the rice mixture is prepared.
In a large pot, arrange all the folded suman and add 1.5 liters of water. Bring it to a boil and reduce to simmer for 45 minutes.