Smash taro well, mix in sugar when the taro is still hot. Add sweet potato starch in. Knead to form a soft ball, add water if needed. Add more flour is your mixture is too wet and more water if the mixture is too dry.
Then divide the dough into 4 equal portions, shape each one into thin long log (around 1.5cm in diameter). Then cut into small dices. Dust some corn flour or sweet potato starch to avoid them from sticky together.