Soak the mung beans for about 7 hours or overnight. Rinse and remove the skins (if using skinned mung beans, just rinse well). Place the beans in a pot, add enough water to cover, and cook until soft. Once cooked, add sugar and cook over low heat, stirring until the mixture thickens and becomes sticky.

Rinse the glutinous rice and soak for about 30 minutes. Drain well. Prepare the banana leaves by letting them wilt and wiping them clean. Cook the black beans until soft, then mix them with the glutinous rice and a pinch of salt.

Depending on the size of the bánh tét, adjust the cooking time. For a roll weighing about 1 1/3 lbs (600 g), cook for 6 hours. To ensure the bánh tét turns out well, wrap and tie tightly. After cooking, remove and rinse the bánh tét in water, then hang in a cool, airy place. The bánh tét tastes best the next day.