Preheat oven to 400°F.
Pare and thinly slice potatoes.
Generously grease bottom and sides of shallow baking dish.
Arrange potato slices in overlapping layers to completely cover bottom of dish.
Spread each layer with soft margarine and sprinkle with salt; repeat until all potatoes are used.
Spread remaining margarine over top.
Bake in hot oven until potatoes are soft in the center, crisp at the edges and brown on the bottom.
During cooking cover top with foil if potatoes are browning too fast.
Takes 45 minutes to 1 hour.