Begin by peeling and evenly cutting 2-3 starchy potatoes into chunks. Place them in a pot of boiling water, cooking for about 15-20 minutes or until fork-tender. Drain and mash smooth in a large bowl.

In a large mixing bowl, combine the mashed potatoes with glutinous rice flour and a sprinkle of sugar. Gradually pour in water, mixing until a soft, pliable dough forms.

Divide dough into equal portions the size of a golf ball. Roll each piece into a smooth log or desired shape.

Heat oil in a skillet over medium heat. Once shimmering, add shaped mochi rolls and fry for 3-4 minutes on each side until golden brown.

Remove from skillet and drain on paper towels. Drizzle soy sauce and sprinkle with sesame seeds and green onions to serve.