Chop red onion into medium dice and toss into a hot 14 to 16-inch saucepan with oil. Add the garlic, chili flakes, potatoes, tomatoes and white wine. Season with salt and pepper. Cook until potatoes are tender.
Bring 8 quarts of water to a boil in large pasta pot and add 3 tablespoons of salt.
Meanwhile, drop the pasta in the salted water and cook according to the package directions, to 1 minute short of al dente. It should still be quite firm. Reserve 1 cup of the pasta water, then drain the pasta in a colander and pour immediately into the saucepan with the potato mixture.
Toss the pasta and cook over high heat for 45 seconds. Stir in the parsley, add some of the reserved water if the pasta seems too dry, and serve immediately.