Parmesan or Pecorino cheese,for serving (optional)
Boil the potatoes: Place the potatoes in a deep pot or saucepan in one layer. Fill with water to cover by at least 2 inches. Sprinkle in 1 tablespoon salt and bring to a boil over medium-high heat. Cover partially and boil until the potatoes are completely tender, about 25-30 minutes. (This is a good time to make your sauce.)
Drain and slice: Drain in a colander set in the sink. Cut a slice into the potatoes with a paring knife to allow steam and moisture to escape. Let rest until cool enough to handle (but not cold), about 15 minutes.
Rice the potatoes: Sprinkle a small amount of the flour onto a clean work surface. Peel the potatoes and cut them into quarters. Pass them through a potato ricer onto the flour-dusted surface. Make a well in the center of the riced potato pile. Let the potatoes cool until they are just slightly warm.
Incorporate the yolk and flour: Sprinkle the one scant cup of flour around the perimeter of the potatoes. Slide the egg yolk into the well; then add the salt. Using a fork, beat the egg and begin to incorporate the potatoes. Keep mixing with a light hand, eventually incorporating some of the flour around the perimeter. Switch to a dough scraper and begin cutting the flour into the potatoes, until you have a crumbly mass.
Rest: Switch to your hands and very lightly press and pat the mixture into a soft ball. It should feel soft and pliant, slightly tacky, and “shaggy” or rough rather than smooth. If the dough is very soft and sticky, incorporate another tablespoon or two of flour. Do not overwork the dough or add too much flour. Cover the dough with a bowl or clean towel and let it rest for a few minutes, no more than 10. Scrape away any stuck bits from the work surface.
Get ready: Line a rimmed baking sheet with a clean kitchen towel and dust with semolina or all-purpose flour. Have a gnocchi board or a fork at the ready. Sprinkle a little flour onto your work surface and have a bowl with more flour nearby. Slice off a piece of dough about the size of a tangerine (about ¼ of the dough).
Roll into ropes: Using your palms, roll out the dough into a rope about the thickness of your finger (¾-inch). Roll the other 3 pieces of dough into ropes. Lightly flour the ropes and use a knife or the dough scraper to cut them into ¾-inch nuggets. Roll the nuggets, one at a time, down the gnocchi board or the tines of the fork. Use your thumb to propel them downward. This creates ridges on one side of the nugget and a groove on the other. Transfer your gnocchi as you shape them to the baking sheet without touching. Flour your workspace and your fingers as needed to prevent the gnocchi from sticking. Continue until you have cut and shaped all the gnocchi. You should end up with about 120 gnocchi.
Dry: Let the gnocchi air dry for 30 minutes. While they are resting, bring a large pot of water to a rolling boil and season with salt. Have your sauce heated and ready before you cook the gnocchi.
Cook the gnocchi: Spoon a small amount of sauce into your serving bowl. When the water is boiling, carefully drop in the gnocchi. Cook in batches to avoid overcrowding the pot. Within 30 to 45 seconds, the gnocchi will begin to float to the surface. Taste one; it should be light and tender but cooked throughout, with no raw flour taste. Using a large skimmer, transfer the gnocchi to the serving bowl and gently toss with sauce. Repeat with the remaining gnocchi, adding them to the bowl and tossing with more sauce as necessary.
Serve: Divide the gnocchi among your serving bowls. Spoon more sauce on top and season with freshly grated cheese if using. Enjoy!
If the gnocchi stick to the surface of the board or the fork, sprinkle on a little more flour.
When on the baking sheet make sure the gnocchi don’t touch, or they will clump together.
Flour your workspace, tools, and hands as needed to prevent the gnocchi from sticking.
Gnocchi are best when cooked and served soon after they are made. Serve immediately, or store shaped gnocchi for up to 2 weeks.
To freeze gnocchi, transfer the baking sheet to your freezer after they finish air drying. Freeze the gnocchi, uncovered, for 1 to 2 hours, until completely firm. Transfer to a zipper-lock freezer bag and return them to the freezer. Boil frozen gnocchi for 30-60 seconds longer than fresh.