In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté until translucent, about 3-4 minutes.
Stir in the minced garlic and cook for another minute till fragrant.
Add sliced carrots, zucchini, and chopped red bell pepper to the pot. Cook for about 5-7 minutes, stirring occasionally until vegetables are slightly softened.
Pour in the vegetable broth and add the canned diced tomatoes, basil, oregano, salt, and pepper. Bring the soup to a boil.
Once boiling, reduce the heat to a simmer and let it cook for 10 minutes to allow the flavors to meld.
Add the cheese tortellini to the soup and cook according to the package instructions (typically 3-5 minutes) until tender.
Stir in the fresh spinach until wilted, about 2 minutes. Adjust seasoning if needed.
Serve hot, garnished with grated Parmesan cheese if desired.