If using glutinous rice, rinse the rice under cold water until the water runs clear. Soak the rice in water for at least 4 hours or overnight. Drain and steam the rice until fully cooked, about 30-40 minutes.
If using cassava, peel and grate the cassava. Squeeze out any excess liquid using a cheesecloth or clean kitchen towel.
Allow the cooked rice or grated cassava to cool to room temperature.
Sprinkle the dry yeast evenly over the cooled rice or cassava. Mix well to ensure the yeast is evenly distributed.
If desired, you can mix in the sugar at this stage for a sweeter tapai.
Transfer the mixture to a clean, dry container. If using banana leaves, wrap portions of the mixture in the leaves and place them in the container.
Cover the container with a clean cloth or lid and let it ferment at room temperature for 2-3 days, or until it develops a sweet, slightly alcoholic aroma and taste.
Once the tapai has fermented to your liking, it is ready to be served.
Enjoy your meal!