Place the flour in the center of a clean work surface and make a well in the center. Add 1/2 cup water and a pinch of salt, blend in the water and knead to form a firm dough. Let rest for 30 minutes.
Meanwhile, in a 12 to 14-inch saute pan, heat the olive oil over high heat until almost smoking and add the celery, onion and pancetta and cook over high heat until browned. Add the tomatoes, chili flakes and salt and pepper, to taste and cook over medium heat for 20 minutes.
Bring 6 quarts of water to a boil and add 2 tablespoons salt.
Roll the rested dough out to the second-thinnest setting on a pasta rolling machine, and cut the sheet into irregular lozenge shapes of about 3/4-inch length. Cook the pasta in the boiling water until it floats to the surface, then drain and toss with the hot sauce over heat for 1 minute to coat. Divide evenly among 4 warmed pasta bowls and top with freshly grated Pecorino Romano.
Recipe copyright 2000, Mario Batali. All Rights Reserved.