Method:

Prepare the Broth: In a large pot, combine the beef, marrow bones, carrot, onion, celery, bay leaf, peppercorns, and salt. Add 12 cups of water and bring everything to a boil over medium-high heat. Once boiling, reduce the heat and simmer for about 3 hours. Stir occasionally and remove any foam that forms on top.

Strain the Broth: After 3 hours, carefully strain the broth through a fine sieve into another pot. Discard the solids (or reserve the meat and vegetables for another dish). Taste the broth and adjust the seasoning if needed.

Cook the Tortellini: Bring the broth back to a boil and add the tortellini. Cook until tender, usually about 3-5 minutes, depending on the size of your tortellini.

Serve: Ladle the tortellini and broth into bowls, and if desired, top with freshly grated Parmesan cheese. Serve immediately and enjoy the rich, flavorful soup!

Variations & Substitutions:

Vegetarian Version: Use vegetable broth instead of meat broth and cheese-filled tortellini instead of meat-filled.

Meat Substitution: You can substitute beef with chicken for a lighter version.

Broth-Free Option: If you're looking for something less brothy, you can serve the tortellini with a simple butter and sage sauce instead.

Tips:

Make-Ahead: You can make the broth in advance and freeze it for later use.

Broth Storage: If you have leftovers, the broth can be refrigerated for up to 5 days or frozen for several months.

Using Leftovers: The cooked beef and vegetables make a great addition to other dishes or can be served with a drizzle of olive oil and some herbs.