– If you haven’t yet dice your leftover potato or diced your onion do so before you start making this dish. – Melt butter in a cast iron skillet over medium low heat.  Add onions with a pinch of salt and pepper.  Cook until onions are softened and slightly translucent. – Add potatoes in with the onions and turn up the heat to medium.  Allow potatoes to cook for a few minutes before stirring.  You want to allow time for the potatoes to fry up and turn golden brown.  Continue cooking and stirring until all sides (well most) are golden brown. – Salt and pepper to taste.  Serve and enjoy!! Careful the inside of the potatoes will be hot.