Heat oven to 350F. Slice all potatoes into halves and place into roasting dish.
Drizzle over the oil and vinegar. Pour over enough hot water to submerge the potatoes and sprinkle over a couple pinches of salt. Place in the oven to cook for roughly 2.5 hours or until all the liquid has evaporated and the potatoes are golden.
Finish off by sprinkling over the green onions and a little more salt. Enjoy!