Mix the flour and salt in a medium bowl using chopsticks or a fork. While stirring, add the water in thirds, letting each addition incorporate before adding the next. Keep stirring until the dough forms large, shaggy clumps with dry bits remaining. Use your hand to knead the dough in the bowl into a single mass while gathering all the dry bits. Once the dough forms a ball, transfer it to a clean work surface and knead until smooth and elastic, about 10 minutes. Cover the dough with plastic wrap and let rest at room temperature for at least 30 minutes or refrigerate for up to 8 hours.
Cut the dough in half and cover one piece with plastic wrap again. Roll the other piece into a rectangle as thin as possible. Generously dust the dough’s surface with flour and fold in half lengthwise. Dust the top with more flour and fold again. Repeat until you have a folded stack of dough about 3 inches wide.
Transfer the dough to a well-floured cutting board and cut into thin strips (⅛- to ½-inch) using a sharp knife. The noodles will expand to about twice their width, so cut according to your desired size. Unravel the noodles and place on a rack or floured surface to dry out. Repeat with the remaining dough. If you have time, let the noodles dry for a few hours.
Bring a large pot of water to a boil. Add the noodles and cook, stirring occasionally, just until tender, 2 to 3 minutes. Drain in a colander, rinse under cold running water until cool, then drain again. Use immediately.