Dice 3 potatoes and boil them in a pot of water to reduce cooking time.

Bring water to a boil in a pot over high heat.

Add the diced potatoes to the boiling water.

While the potatoes are cooking, prepare the sauce by mixing soy sauce, oligosaccharide, mirin, and water.

Drain the cooked potatoes and mash them in a bowl until smooth.

Add 2 tbsp of potato starch and 1 pinch of salt to the mashed potatoes and mix well.

Shape the dough into small round pieces and flatten them slightly.

Heat 1 piece of butter in a frying pan over low heat.

Place the mochi pieces in the pan and cook until golden brown on both sides.