Place potatoes in pot and fill 2 inches above with cold water. Bring to a boil then turn heat to medium and cook partially covered for 30-35 minutes or until potatoes are tender. If a sharp knife slides through the potatoes, they are ready to be drained.
Drain potatoes in a colander, then spread out on a board to cool. Once potatoes are cool enough to handle, peel and discard all the skin. Run the still warm potatoes through a ricer.
Place the riced potatoes on a large work surface. Once potatoes are fairly cool, sprinkle with the salt, the flour, and drizzle the egg.
Fold the mixture together with a bench scraper to incorporate the flour into the potatoes. Form a rough mass by kneading for 30-45 seconds, but don't overdo it. If too wet use a bit more extra flour, working hard to use no more flour than necessary.
Once a cohesive ball has been formed place it to the side. Clean the work surface completely and sprinkle flour onto the work surface.
Grab 1/6 of the dough or about the size of a lemon and begin rolling the dough into a string about 1/2 to 3/4 of an inch thick.
Once completely rolled out, cut with a sharp knife or bench scraper individual pieces about 3/4 to 1 inch long. Gnocchi can be grooved with a gnocchi paddle, fork, or left as is.
Place the cut gnocchi on a parchment paper lined baking sheet that has been sprinkled with semolina flour or all-purpose flour. Make sure to keep the gnocchi pieces separated to avoid any sticking. Repeat with remaining dough.
Once a full tray has filled up with gnocchi, place it in the freezer for 2- 3 hours to harden. Gnocchi can be cooked right away or saved in freezer bags for up to 3 months.
To cook gnocchi, bring a large pot of salted water to boil and drop in a small batch (about 15-20 gnocchi at a time). Once the gnocchi float to the top, remove with a slotted spoon and place into your choice of sauce. Enjoy!