Peel potatoes if desired. Cut in half and place in large pot. Cover with cold water.
Bring water to a boil and cook until potatoes are just tender (about 10 minutes). Drain.
Place potatoes in large bowl and cover with cold water. Place in fridge over night.
Drain potatoes. Shred with hand grater or food processor.
To cook right away: Heat frying pan over medium-high heat. Add butter or margarine. Place shredded potatoes in pan. Cook for approximately 5-7 minutes or until bottom is browned. Flip potatoes and cook until browned. Season with salt and pepper.
To freeze: Spray freezer-safe container with cooking spray (I use a plastic ice cream tub). Place a layer waxed paper in the bottom and spray w/ cooking spray. Place a layer of potatoes in container (enough for 1 meal). Place another piece of waxed paper on top of potatoes and spray with cooking spray. Continue layering in this way until all potatoes are used. Freeze until ready to use. Cook as directed above (will take longer).