- Heat a large sauté pan over medium heat. Add the olive oil and onion, and cook until the onion is translucent, 8-10 minutes. Add the chile flakes and garlic, and cook for another 2 minutes, until fragrant. Stir in tomatoes and simmer uncovered for 20 minutes. Bring a large pot of salted water to a boil. Cook the pasta according to package instructions. Save ½ cup of pasta water, then drain. Add the drained pasta to the sauce. Stir well, adding a little pasta water if needed to loosen the sauce. Season with salt to taste. Serve hot.