Austrian Kartoffelknoedel (Potato Balls)

500 grams potatoes, cooked
40 grams butter, softened
1 egg
50 grams semolina flour, as needed
salt

Grate (or use a potato press) the cooked potatoes. Mix the butter and egg together then add the semolina and salt. Mix this with the potatoes, adding flour as needed until you have a firm dough mixture. Form into balls (a little smaller than a baseball) and boil in salt water for 10 minutes.