In food processor, pulse flour and salt to combine. With motor running, gradually drizzle in hot water until mixture clumps together. (See Tip)
Remove dough to work surface and knead, folding it toward you and then pressing it with the heel of your hand; rotate. Repeat until smooth without adding any flour, 2 to 3 minutes (adding flour 1 tsp at a time if sticky).
Wrap in plastic wrap and let stand at room temperature for 30 minutes.
Divide dough into quarters. Working with 1 piece of dough while keeping the rest covered, roll or press flat enough to feed into pasta maker on thickest setting (dusting with flour if sticking).
Feed dough through pasta machine on thickest setting. Fold dough in thirds like a letter, then repeat on same setting.
Continue running dough through rollers, decreasing thickness by one notch each time by increasing the number setting until you reach 5 or 6, depending on how thick you like your pasta.
Attach desired noodle accessory to machine; lightly dust dough strip with flour, then feed it through noodle cutter. Separate noodles and toss with some flour to prevent sticking.
Alternatively, using a rolling pin, roll dough on work surface, without additional flour, to 1/16-in (1½-mm) thickness. Dust with semolina flour and fold into thirds from the shorter end. Cut into ribbons as wide as desired. Unfurl pasta and toss with more semolina on a baking sheet to dry.
In large pot of lightly salted boiling water, cook pasta until al dente, 2 to 4 minutes. Using a slotted spoon or spider, remove pasta to serving bowls. (This will ensure any excess semolina is left at bottom of pot.) Serve with a pasta sauce, like the 10-Minute Sugo or Thick & Glossy Pomodoro.