How to Make It
Preheat the oven to 400°. Sprinkle the potatoes with a pinch of kosher salt and wrap them individually in foil. Bake for 1 hour, or until tender. Let the potatoes cool slightly, then halve lengthwise. Scoop out the potato flesh and press it through a ricer or a fine sieve into a large bowl. Let cool slightly.
In a small bowl, beat the egg with the egg yolk, parsley and vinegar. In a medium bowl, mix the flour with the table salt, pepper and nutmeg. Add the egg mixture to the warm potatoes and mix with your hands until just blended. Gently incorporate the flour mixture. Shape the dough into a ball, cover with a towel and let stand for 10 minutes.
Bring a large pot of salted water to a boil. Divide the dough into 6 pieces and roll each piece into a 1/2 -inch thick rope. Cut the ropes into 1-inch lengths.
Fill a large bowl with ice water. Add one-third of the gnocchi to the boiling water and cook until they rise to the surface, about 1 minute. Using a slotted spoon, transfer the gnocchi to the ice water to cool, then drain and transfer them to a bowl. Toss with a bit of olive oil. Spread the gnocchi on a baking sheet lined with plastic wrap. Repeat with the remaining 2 batches of gnocchi.