To Make Japanese Dumplings
In a large mixing bowl, add shiratamako, joshinko and sugar, mix well.
Add in warm water bit by bit while kneading the dough slowly until smooth and soft.
Divide the dough into 8 equal portions, then divide each portion into 3 equal portions. Roll each portion into a ball.
In a large pot of boiling water, gently add in the dumplings. After they start floating on the surface, cook for 1 more min. Remove and transfer to ice water.
To Make Coating
Wet the Japanese mortar and pestle, then grind the black sesame seeds in batches. Mix well with sugar.
To Serve
Drain the dumplings and put 3 balls into each bamboo skewer. Coat with the sweet black sesame mixture and serve.