Let the potatoes cool for 10 minutes after baking them. peel them and run the potatoes through a potato rice, or grate them on the large holes of a box grater. cool them to lukewarm, another 10 minutes. Add the egg and salt, mix to combine. Add ½ cup of the flour, and see if this is enough to form the dough, add another ½ cup of flour and mix again. Add ¼ cup flour and see if this is enough to form a dough that doesn't easily stick to your hands. If not add the last ¼ cup of flour, a tablespoon at a time, until the dough is a good consistency - soft and a little sticky, but able to holds it shape enough to be rolled into a rope. Knead the dough together briefly on the counter - just for a minute.