- 3 1/2 pounds oxtails
- 2 pounds beef shank bones
- 2 pounds bone-in beef short ribs
- 1 (6-ounce) can tomato paste
- 1/4 cup red wine vinegar
- 3 medium onions, coarsely chopped
- 3 carrots, coarsely chopped
- 3 celery stalks, coarsely chopped
- 15 garlic cloves, peeled
- 1 tablespoon olive oil
- 1 bunch fresh parsley
- 10 fresh thyme sprigs
- 3 bay leaves
- 20 black peppercorns
- 1/2 ounce dried porcini mushrooms
- 1 1/2 teaspoons salt
- 1/2 teaspoon ground black pepper
- Preheat the oven to 375°F.
- Brush the oxtails, shank bones, and short ribs with the tomato paste and transfer to two rimmed baking sheets. Roast, turning occasionally, until browned, 45-50 minutes. Transfer oxtails, shank bones and short ribs to a large stockpot; add 6 quarts water and the vinegar and bring to a boil. Immediately reduce the heat to medium and simmer 1 1/2 hours, skimming off the fat and any foam.
- Meanwhile, combine the onions, carrots, celery and garlic in a bowl; add the oil and toss to coat. Spread the vegetables onto two rimmed baking sheets and roast, stirring occasionally, until lightly browned, 40-45 minutes. Add the vegetables, parsley, thyme, bay leaves, peppercorns and porcini mushrooms to the stockpot after it has simmered the initial 1 1/2 hours. Return to a simmer then reduce the heat to medium-low so that the liquid is barely simmering, just a few bubbles here and there. Continue cooking the soup for 12 hours. (You may have to adjust the heat to keep it from cooking too vigorously.)
- Strain the soup through a wire mesh sieve. You can discard the solids or remove the beef from the bones and save for another meal. Skim fat from the soup. You should have 3 quarts of liquid: if you have more pour the soup into a clean pot, bring to a simmer over medium heat and cook until reduced to 3 quarts. Season the soup with salt and pepper.