1. Spray a large nonstick skillet with vegetable cooking spray. Heat over medium heat. Add the red onion, bell pepper, and water. Cover and cook for 3 minutes. Uncover and add green onion. Cook for 2 minutes. Transfer the mixture to a plate.
2. Add the tomatoes with liquid and half of herbs to skillet; breaking up tomatoes with a spoon. Simmer for 10 minutes.
3. While tomatoes are simmering, cook pasta according to package directions, but do not add salt. Set aside 1/2 cup of pasta cooking water. Drain pasta and place in a large bowl. Stir in onion mixture, tomatoes, and enough pasta water to thin sauce. Stir in mozzarella. Sprinkle with remaining herbs and parmesan and serve.