For the frankfurters with mashed potatoes, first peel the potatoes and cut them into thirds. Put them in a container with water so that they are not too greasy. Then boil the cut potatoes in a pot with water and salt until soft.
Mash the strained potatoes with a masher. Stir in milk and butter. Stir and add milk until it reaches the right consistency.
Cut the frankfurters at the ends once lengthwise and once widthwise and fry them in a pan with oil.