1. Heat oil in a 3-quart saucepan over medium-high heat. Add onions, bell peppers and zucchini and cook 4 to 5 minutes, until tender. Add garlic and cook 30 seconds more. Stir in tomatoes with juice, tomato paste, 1-1/2 teaspoons salt, oregano and basil; bring to a boil, then reduce heat to medium-low. Cover and cook 20 minutes until vegetables are very tender.
2. Start to cook pasta according to package directions.
3. Meanwhile, combine ricotta and 1/4 teaspoon salt in a small bowl; set aside. Puree tomato sauce in blender in batches until smooth. Transfer each batch to a large bowl then return to saucepan. Bring sauce to a boil.
4. Drain pasta and toss with half the sauce (2-1/2 cups) in a large serving bowl. Divide pasta among 4 serving plates. Top with remaining sauce and ricotta; sprinkle with parsley.