In large saucepan over medium heat, heat oil; cook onion, garlic, carrot and celery about 5 minutes, or until softened. Add pesto, basil, oregano and chili flakes; cook 1 minute.
Add tomatoes, chicken broth, salt and pepper; bring to boil. Reduce heat and simmer about 20 minutes, or until slightly thickened.
In blender or using immersion blender, puree tomato mixture; return to pan and bring to simmer. Add tortellini; cook 8-10 minutes, or until tender. Sprinkle with parsley and parmesan.