In a large bowl, combine the Joshinko and the Shiratamako. Gradually add warm Water while stirring until the mixture comes together into a soft, pliable dough; knead briefly until smooth and slightly elastic.
Divide the dough into equal pieces (about the size of a ping-pong ball) and roll each piece between your palms into a smooth round ball.
Bring a pot of water to a gentle boil. Drop the dango balls in and cook until they float, plus another 1–2 minutes to ensure they are cooked through; scoop them out with a slotted spoon and immediately transfer to a bowl of cold water to firm up.
Thread 3–4 cooled dango onto each skewer so they sit snugly together.
To make the mitarashi glaze, combine Sugar, Soy Sauce, Mirin, Sake and a splash of water in a small saucepan. Warm gently and stir until the sugar dissolves and the mixture comes to a simmer.
Mix the Potato Starch with a little cold water to form a smooth slurry, then whisk this into the simmering sauce. Cook briefly until the glaze thickens to a glossy, pourable consistency—adjust the balance of sweetness or saltiness to taste.
Brush or dip the skewered dango in the warm glaze, then place the skewers under a hot broiler, on a grill, or in a hot skillet for a minute or two to caramelize and slightly char the surface—turn and watch carefully so they don’t burn.
Give the skewers another light brush of glaze and serve warm for the best texture and flavor.
