Imo mochi (Hokkaido potato mochi)

Step 1: Boil 14 oz floury potatoes in unsalted water for 12–15 minutes, until a knife slides through easily. Drain well and let them steam dry in the pan for a minute.

Step 2: Mash the potatoes while hot until there are no lumps, then work in 1 ¾ oz potato starch and ¼ tsp salt with a spoon and then your hands, until you have a smooth, soft dough that holds its shape. If it sticks to your fingers, add a little more starch.

Step 3: Divide the dough into 8 pieces and flatten each into a disc about 1.5 cm thick. If using 1 ⅜ oz mild cheddar or mozzarella, press a cube into the middle and fold the dough over to seal it completely, so it doesn't leak in the pan.

Step 4: Heat 1 tbsp vegetable oil in a non-stick frying pan over a medium heat. Fry the discs for 3–4 minutes on each side, until golden and crisp and they feel springy when pressed.

Step 5: Mix 1 tbsp soy sauce, 2 tsp sugar and 1 tbsp water. Turn the heat to low, add ⅓ oz butter, then pour in the soy mixture and turn the patties in it for about 1 minute, until glossy and the sauce has almost gone. A common mistake is adding the glaze over a high heat: the sugar burns before it coats.

Step 6: Serve warm. Leftovers keep in the fridge for a day; reheat them in a dry pan until hot through.