Preheat your oven to 350°F (175°C).

Season the lamb shanks generously with salt and black pepper.

In a large, heavy-bottomed pot or Dutch oven, heat the olive oil over medium-high heat. Once hot, add the lamb shanks and sear them on all sides until browned, about 5-7 minutes. Remove the shanks and set aside.

In the same pot, add the chopped onion, garlic, carrots, and celery. Sauté for about 5 minutes, or until the vegetables are softened and fragrant.

Pour in the pomegranate juice and balsamic vinegar, scraping the bottom of the pot to release any browned bits. Bring the mixture to a simmer.

Stir in the chopped rosemary, thyme, beef or vegetable broth, and bay leaves. Return the lamb shanks to the pot, ensuring they are submerged in the liquid.

Cover the pot with a lid and transfer it to the preheated oven. Braise the lamb shanks for 2 to 2.5 hours, or until the meat is tender and falling off the bone.

If you prefer a thicker gravy, remove the shanks once they are done and set them aside. Bring the braising liquid to a boil on the stovetop and reduce it by half. You can mix cornstarch with a little water to create a slurry and add it to the boiling liquid to thicken if desired.

Serve the lamb shanks hot, drizzled with the rich root vegetable gravy. Garnish with fresh pomegranate seeds and sprigs of rosemary.