Here's the recipe:
sweet potato 500 g (2 pieces)
sweet potato starch 400 g ( I used tapioca)
brown sugar (I used 1 cup)
Cut sweet potato into cubes. Steam until soft and pound it in puree.
Add sugar and sweet potato starch, whisk well to blend. Knead into long cylinder; cut for about 1.5 cm cubes.
Deep fried sweet potato cubes in oil for about 30 seconds; stir rapidly and press cubes lightly to make cubes into balls. Transfer to plate and ready to serve.