Combine 3-1/2 cups flour and salt in a large bowl. Make a well in the center. Pour water into well and stir together, forming a ball.
Turn onto a floured surface; knead until smooth and elastic, about 8-10 minutes, adding remaining flour if necessary to keep dough from sticking to surface and hands (dough will be stiff). Shape into a rectangle; cover and let rest for 30 minutes.
Divide dough into fourths. On a floured surface, roll each portion into a 16-in. x 8-in. rectangle. Dust dough with flour to prevent sticking while rolling. Cut crosswise into 1/8-in. slices. Separate noodles onto clean towels; let dry overnight (let dry in the shape the noodles will be stored in). Package dry pasta.
To cook fettuccine: Fill a Dutch oven three-fourths full with water. Bring to a boil. Add noodles; cook, uncovered, until tender, 8-10 minutes. Drain.
Test Kitchen tips
In a large bowl, combine 1 pound chopped plum tomatoes, 1/3 cup pesto, 1/4 teaspoon salt and 1/4 teaspoon pepper. Toss with cooked pasta; sprinkle with Parmesan cheese.
Add chopped fresh herbs for a flavor punch.
For a more traditional Italian pasta, substitute 2 eggs for 1/2 cup of the water.