Preheat your oven to 325?F (160?C).

Season the lamb shanks with salt and pepper.

In a Dutch oven, heat olive oil over medium-high heat. Sear the lamb shanks on all sides until browned, about 8-10 minutes. Remove and set aside.

In the same pot, add onion, celery, carrots, and garlic. Saut? until softened, about 5 minutes.

Pour in the white wine, scraping up any browned bits from the bottom of the pot. Let it simmer for 2-3 minutes.

Add the beef broth, diced tomatoes, thyme, rosemary, and bay leaf. Return the lamb shanks to the pot, ensuring they are submerged in the liquid.

Cover and transfer to the oven. Braise for 2-2.5 hours, or until the meat is tender and falling off the bone.

In a small bowl, mix lemon zest and parsley to make the gremolata.

Serve the lamb shanks topped with gremolata over a bed of polenta or risotto.