First, rinse the beans, dried lily bulb pieces, and sweet rice under cold water. Add them to a large bowl, and cover with a few inches of water. Soak for at least 8 hours or overnight.
Drain the beans, lily bulb, and rice, and transfer to a large pot along with 8 cups of fresh water. Bring to a boil, cover, and simmer for about 1 hour, or until the beans are very soft and beginning to break down. Fresher beans cook faster, while older beans can take a while to cook through, so monitor the cooking process and adjust the cooking time accordingly.
If using sago or tapioca, add it to the soup after it’s been cooking for about 40 minutes. It will take about 20 minutes for them to cook through (they will be completely translucent).
Finally, stir in your sweetener to taste. You can also refrain from adding sugar at this point, and each person can sweeten their individual bowls to taste.
Notes
Nutrition info does not include optional ingredients.If making ahead, turn off the heat at the 50 minute mark and keep the pot covered. This will prevent overcooking.Prep time does not include 8 hours soaking time. You can also make this soup in the Instant Pot, which cuts out the pre-soaking step. Add dried mung beans, dried lily bulb, sweet rice, and water to your Instant Pot. Seal the vent, cover, and cook on the bean/chili setting. Allow the pressure to release naturally. If adding sago, cook it separately: Fill a medium pot about two thirds of the way with water, and bring it to a rolling boil. Stir in ½ cup sago or tapioca (DO NOT add it until the water is at a full boil!). Simmer for 20 minutes, or until the sago/tapioca is completely translucent. If after 20 minutes, the pearls still have a white center, turn off the heat, cover, and let sit in the hot water for another 5-10 minutes, or until they’re fully translucent. Drain through a fine-mesh strainer, rinse in cold water to cool, then soak in a bowl of cold water and set aside. When the soup has finished cooking, drain the pearls, and add to the soup.