Mix pasta, tomatoes, onion, garlic, red-pepper flakes, basil, oil, 2 tsp. salt, ¼ tsp. pepper,+water in large straight-sided skillet. Bring to boil over high heat. Boil mix, stirring+turning pasta frequently with tongs, til pasta is al dente+water has nearly evaporated, about 9 min. Season to taste divide among 4 bowls,+garnish with basil. Serve with oil+Parmesan.