First Step: Prepare the Meat: Pat dry the beef oxtail and beef shank pieces. Season with 2 tablespoons of salt and freshly ground black pepper. If desired, heat 2 tablespoons vegetable oil in a large heavy stockpot or Dutch oven over medium-high heat and brown the meat on all sides for 5-6 minutes per side. Remove the browned meat and set aside.

Second Step: Sauté Aromatics: In the same pot, add chopped onions, diced garlic, and sliced celery. Cook over medium heat for 9-10 minutes until softened and fragrant. If using tomato paste and Worcestershire sauce, stir them in and cook briefly to integrate flavors.

Third Step: Deglaze and Add Liquids: Add beef broth or water to deglaze the pot, scraping up browned bits for extra flavor. Return oxtail, beef shank, and any bones to the pot. Add remaining water to ensure ingredients are submerged (totaling about 20 cups). Add optional bay leaf, thyme, and saffron if using.

Fourth Step: Simmer Slowly: Bring to a boil, then reduce heat to low and cover loosely. Simmer gently for 2 ½ to 3 hours. Occasionally skim foam and excess fat from the surface for a clear broth. The meat should become tender and gelatinous.

Fifth Step: Add Vegetables: Add carrots, potatoes, celery, cabbage, corn, tomatoes, and zucchinis. Bring to a boil again, then reduce heat to a low simmer. Cover and cook for an additional 30 minutes until vegetables are tender but still hold shape.

Final Step: Season and Finish: Stir in ground coriander, additional salt to taste, freshly ground pepper, and fresh cilantro or parsley. Cook uncovered for 10 minutes to meld flavors. Optionally, remove meat from bones, shred, and return to the pot for easier serving. Serve hot with lime wedges or optional garnishes like salsa casera or bone marrow spread on warmed corn tortillas.