Wash the potatoes, but don’t scrub too hard – you want to keep the skin on. Cut each potato in half, or in quarters if they’re big.
Place the potatoes on a plate, cover with cling wrap and microwave on high for 3 to 4 minutes (or boil them for 3 to 4 minutes).
Heat the vegetable oil in a pan and fry the potatoes over medium heat for 5 to 6 minutes, or until the potatoes have browned. Then wipe away the excess oil from the pan with a paper towel.
Add the teriyaki ingredients to the pan and cover. Simmer over medium-low heat, flipping the potatoes occasionally, until they have cooked through and the liquid has almost completely evaporated, about 5 to 6 minutes. Dish out and enjoy!