Preheat oven to 350 degrees. Peel and slice into a greased casserole dish - 5 medium potatoes. Sprinkle with 1 package dry onion soup mix. Fill with water to 1/2 inch from the top. Sprinkle with few grains pepper. Dot with 2 tablespoons butter. Bake 1 1/2 hours or until potatoes are tender. For more flavor, add a little bit of salt.