Making gnocchi takes practice; like pastry, it’s as much about finding the right touch as it is about the ingredients. Use as little flour as possible and be careful not to overmix the dough. Choose boiling potatoes for the right texture; fresh, non-boiling potatoes will be too moist, while Russets or bakers will be too mealy.

Steps

1. Place the potatoes in a large saucepan and cover with water. Bring to a boil and cook at a medium boil until tender. Test with a wooden skewer and, when done, drain well. Using a dishcloth to protect your hands, peel the potatoes while they’re still hot.
2. Press the potatoes through a potato ricer onto a lightly floured work board. Start fluffing in the flour with your hands, starting with the smaller amount — the less flour, the better — until well incorporated. Knead to a soft, smooth mixture. Cover with a towel to keep the mixture warm while you are working.
3. Bring a saucepan of salted water to a boil.
4. Before shaping all the dough, test a few dumplings first: Break off a walnut-size piece of dough and, on a lightly floured surface, roll it into a ¾-inch-thick rope. Cut it crosswise into ¾-inch pieces, then shape the gnocchi by pressing it against the tines of a fork. Drop test gnocchi into the saucepan of boiling water and simmer; once they pop up to the surface, cook for another 10 to 15 seconds, then scoop out with a slotted spoon or skimmer.
5. If the gnocchi holds together and has a tender, light texture (best tested by tasting), proceed with shaping the rest of the dough. If the gnocchi falls apart during cooking, add a bit more flour to the dough, gently kneading it by hand for about a minute. Shape the gnocchi, placing them on a lightly floured sheet pan until ready to cook.
6. Bring 6 quarts of water to a boil in a wide pot and salt well. Cook gnocchi in batches, dropping them into the boiling water. The gnocchi will sink to the bottom, then float to the surface. Let them cook 10 to 15 seconds longer, until tender, then remove them with a large slotted spoon or skimmer to a warm serving platter.
7. Toss with the arugula pesto, thinned with gnocchi water if necessary, and garnish with grated Parmesan cheese.