Chewy taro balls in sweet soup with vibrant purple color are a beloved Taiwanese-inspired dessert. A fun family treat with fresh, natural taro flavor.
Steam the peeled and cubed taro (and sweet potato if using) for 20 minutes over high heat until soft and easily pierced with a fork.
While hot, mash taro thoroughly until smooth; transfer to a large mixing bowl and allow to cool slightly.
Gradually add tapioca starch and sugar to the mashed taro, mixing and kneading until a cohesive, slightly sticky dough forms. Add water a tablespoon at a time if too dry.
Divide the dough and roll into long ropes on a floured surface, then cut into small bite-size pieces.
Bring a pot of water to a rolling boil and gently drop in taro balls. Boil until they float for 2–3 minutes, then simmer for 2 minutes more for ideal chewiness.
In a separate saucepan, dissolve rock sugar or brown sugar in 4 cups of water over medium heat to make the sweet soup. Stir until fully dissolved.
Transfer cooked taro balls directly into the hot sweet soup. Serve warm, or chill before serving for a refreshing treat.