01 - Peel the potatoes and cook them in salted boiling water until tender. Drain and allow to cool slightly.
02 - Mash the potatoes until smooth and let them cool completely.
03 - In a large bowl, combine the cooled mashed potatoes, flour, egg, and salt. Mix until a dough forms.
04 - Divide the dough into equal portions and roll into balls. Flatten slightly.
05 - Bring a large pot of salted water to a boil. Drop the dumplings into the water and cook until they float to the surface, about 5-7 minutes.
06 - In a skillet, melt the butter over medium heat and add the sliced onions. Cook until the onions are golden brown and crispy.
07 - Remove the dumplings from the water and serve topped with the fried onion butter.