Boil the potatoes until tender, then peel and mash them thoroughly while still warm. Allow the mashed potatoes to cool completely to room temperature.

On a clean surface, combine the mashed potatoes, flour, egg, and salt. Gently knead the mixture until it forms a soft, cohesive dough, being careful not to overwork it.

Divide the dough into several portions and roll each into a long, thin rope (about 1/2 inch thick). Cut the ropes into 1-inch pieces and, if desired, roll them over a fork to create ridges.

Bring a large pot of salted water to a gentle boil. Carefully drop the gnocchi into the boiling water and cook until they float to the surface, which usually takes 2-3 minutes. Remove them with a slotted spoon.

Serve the cooked gnocchi immediately with your favorite sauce or a simple dressing of butter and sage.