Put mashed potatoes, salt, sugar, milk and butter in a bowl and mix them up real good, just like you were going to make mashed potatoes to eat. Chill in refrigerator long enough so that it is thoroughly chilled. Aunty Alfta usually just leaves it there over night then gets it out to fix the next morning. Cut in the flour until you have a good consistent dough. Aunty Alfta finds she some times has to add a little more flour, sometimes up to 2 cups. Next you take the dough and divide it into two balls. Roll each ball into a long roll and divide each roll into six pieces. Take each piece and roll it into a ball and you are ready to roll it out. Take a dough ball and press it flat some and then roll it flat just like you were rolling out some pizza dough like you were making a crust for a thin crust pizza or for a pie crust. Then take it too the pan. Put down a half teaspoon of butter (do this before cooking each lefse) and just slap that lefse down there and cook it until brown spots appear then turn it and cook the other side until brown spots appear it on it. Aunty Alfta has found that you can tell its ready to turn when you see bumps appear in the lefse dough. Clarified butter is better because if you dont use it, half the butter will go up in steam every time you add it to the pan, which means youll have to add more to make up. If your kitchen is warm at all dont lay the lefse on top of each other without wax paper between or youll never get them apart! Aunty Alfta found that out the hard way! You can also freeze lefse. They thaw out really easily.