. Generously season 4 lamb shanks with salt and pepper on all sides.

Heat 2 tablespoons of olive oil in a large, heavy-based pot or Dutch oven over medium-high heat.

Place the lamb shanks in the pot and sear them on all sides until they are browned, about 2-3 minutes per side. This step helps to lock in the flavor and adds a rich color to the meat.

Once browned, remove the lamb shanks from the pot and set them aside.

In the same pot, add 1 large chopped onion, 2 chopped carrots, and 3 chopped celery stalks. Sauté the vegetables for about 5 minutes, or until they are softened.

Add 4 minced garlic cloves and 2 tablespoons of tomato paste to the pot. Cook for an additional 2 minutes, stirring frequently to prevent burning. This will enhance the depth of flavor in your dish.

Pour in 2 cups of red wine (optional), and use a wooden spoon to scrape the bottom of the pot, lifting any browned bits. Allow the wine to simmer for 2-3 minutes to reduce slightly. This step adds a rich, complex flavor to the dish.

Pour in 4 cups of beef or chicken broth and 1 can (14 oz) of crushed tomatoes. Add 2 sprigs of fresh rosemary, 2 sprigs of fresh thyme, 2 bay leaves, and, if desired, a cinnamon stick, 1 teaspoon of ground cumin, and 1 teaspoon of paprika. Stir everything together to combine the flavors.

Place the seared lamb shanks back into the pot, ensuring they are submerged in the liquid.

Bring the pot to a simmer over medium heat. Once simmering, reduce the heat to low, cover the pot with a lid, and let it cook for 2.5 to 3 hours. Alternatively, you can transfer the pot to a preheated oven at 160°C (325°F) and cook for the same amount of time.

After 2.5 to 3 hours, check the lamb shanks. They should be tender and falling off the bone. If they are not yet tender, continue cooking for another 30 minutes.

If you prefer a thicker sauce, remove the lamb shanks from the pot and set them aside. Mix 2 tablespoons of cornstarch with 2 tablespoons of cold water in a small bowl to create a slurry. Stir the slurry into the cooking liquid and bring it to a simmer. Cook for a few minutes until the sauce thickens.

Serve the lamb shanks on a warm plate, spooning the rich sauce over the top.