With the rack in the middle position, preheat the oven to 350°F (180°C).
Prick the potatoes with a fork and place directly on the oven rack. Bake for 1 hour or until tender.
Remove the potatoes from the oven, peel while still hot and press through a potato ricer. Transfer to a lightly floured surface. Sprinkle with the salt. Let cool.
Sprinkle with the flour and add the egg. With your hands, gently combine the ingredients. Knead the mixture until just smooth. Do not overwork the dough or it will become overly elastic. If the dough is too sticky, add a bit of flour. Shape into a disc.
Without delay, divide the dough into 6 pieces. On a floured work surface, roll each piece into a long ½-inch (1 cm) thick rope. With a knife, cut each rope into ½-inch (1 cm) gnocchi. Lightly dust with flour. If desired, roll the gnocchi over a gnocchi board or with a fork until rounded and grooved. Set aside on a lightly floured baking sheet. The gnocchi can be frozen at this stage, if desired.
In a large pot of simmering salted water, gently drop one-third of the gnocchi at a time. Once they float to the surface, let simmer for 2 minutes or until cooked through. With a slotted spoon, drain the gnocchi and add to warmed oregano tomato sauce. Adjust the seasoning.