Combine Milk (150 milliliter), Potato Starch (2 tablespoon) and Brown Sugar (2 tablespoon) together in a pot until all of the flour and sugar are well mixed with no lumps.
Prepare ice water in a bowl. Put the pot on the stove and heat to medium heat. Keep stirring until it becomes sticky and glutinous and has a shiny, glossy look. Transfer to cling wrap and wrap it around. Shape it into a rectangle.
Put the mochi into the prepared ice water. Meanwhile, combine the Brown Sugar (1 tablespoon) and Water (1 tablespoon) together and bring to a boil. Then turn to low heat and simmer until it reaches a syrup texture.
Put half of the Roasted Soy Bean Flour (100 gram) on parchment paper. Take the cooled down mochi out and coat with soy bean powder. Use a knife to cut mochi into cubes and put more soy bean powder on. Coat evenly.
Pour the brown sugar syrup over the mochi just before serving. Bon Appetite.