In a large pot, heat olive oil over medium heat. Add chopped onion, diced carrots, and diced celery. Sauté for about 5–7 minutes until the vegetables soften and the onion becomes translucent. Stir in minced garlic and cook for an additional minute until fragrant.

Pour in vegetable or chicken broth and add diced tomatoes (with juices). Stir in Italian seasoning, along with salt and black pepper. Bring to a gentle simmer for about 5 minutes.

Increase the heat to high and bring the soup to a rolling boil. Reduce the heat to low, allowing it to simmer gently.

Add tortellini to the boiling soup. Cook for about 3–5 minutes for fresh tortellini or follow package instructions for frozen tortellini, which typically takes 7–10 minutes.

In the final minutes of cooking, stir in fresh spinach or kale, letting it wilt into the soup.

Ladle the steaming soup into bowls and top each serving with freshly grated Parmesan cheese and optional parsley.