Grate coarsly your potatoes. In large bowle rinse the potatoes with cold water. Drain and repeat once again to get rid of as much starch as possible.

Take wring out as much water as its possible, spread potatoes on paper towel and pat dry.

in large pan melt the butter. Spread your potatoes in thin layer and on medium high heat, season with salt and pepper and cook until they are brown (it takes 3-5 minutes). Flip them around, dont bother if you tear them a little, and cook them on the other side till they are brown as well (another 3-5 minutes).