Coat a large skillet thoroughly with nonstick spray. Over medium heat, heat potatoes for about 10 minutes, stirring frequently and sprinkling generously with no-salt seasoning. Transfer to casserole dish and sprinkle with shredded cheese and crumbled bacon. Bake in oven about 5 minutes; sprinkle with scallions, then return to oven for another few minutes, until cheese is melted. Serve immediately with a hearty dollop of sour cream.