In a large Dutch oven or stockpot, cook the ground Italian sausage over medium heat until browned. Add the chopped onion midway through and continue cooking until the sausage is fully browned and the onion is softened.

Reduce heat to low and add minced garlic, dried basil, oregano, parsley, thyme, and red pepper flakes. Stir for about 1 minute until fragrant.

In a small bowl, whisk tomato paste with about ½ cup of beef broth. Add this mixture to the pot along with the remaining beef broth, vegetable (or chicken) broth, and fire-roasted tomatoes. Bring the soup to a low boil over medium heat.

Once the soup reaches a boil, reduce heat to a simmer. Add the cheese tortellini and cook for 10-15 minutes, or until the tortellini are tender.

Stir in arugula or spinach until wilted. Adjust seasoning with salt and pepper if needed.

Ladle the soup into bowls and top with grated Parmesan cheese. Garnish with fresh thyme or basil if desired.