Wash the potatoes and boil for 40-45 minutes or until they are soft. Check the cooking level of potatoes with your fingertip avoiding to break the peel. in this way the potatoes don't absorb water during the boiling step.
Drain the potatoes, peel and crush on a work surface with a fork or potato ricer. Spread the purée on the surface to promote cooling. When the potatoes are lukewarm, create a mound and add salt and 100 grams of flour and mix to a firm dough. Even if the dough seems sticky, use only the remaining flour to shape the gnocchi with the fingertips without adding other flour. the secret to fluffy gnocchi is to use a small amount of flour and work the dough quickly.
Cut the dough in pieces and use the remaining flour to keep the work surface and the dough lightly floured. Roll each piece into a rope about 1 inch in diameter and cut them. Use a fork or a gnocchi board to shape them.
Boil the water and add salt (add more salt than usual since there is a small amount of it in the gnocchi). Cook the gnocchi until they rise to the surface of water. Remove the cooked gnocchi with a skimmer, shake off the excess water and serve with the pesto.