1-First Step: Preheat your oven to 180°C (350°F). Pat the lamb shanks dry and season with salt and pepper. Heat 2 tablespoons olive oil in a large heavy pot over high heat, then brown the shanks in batches for about 5 minutes each before removing and draining excess fat.

2-Second Step: Reduce heat to medium-low and add the remaining tablespoon of olive oil. Sauté the onion and garlic for 2 minutes, then add carrot and celery and cook another 5 minutes until the onions are translucent and sweet.

3-Third Step: Add red wine, chicken stock, crushed tomatoes, tomato paste, thyme, and bay leaves, stirring to combine. Place the lamb shanks back into the pot, submerging them mostly in the liquid, and bring to a simmer on the stove.

4-Fourth Step: Cover the pot and transfer to the oven for 2 hours. Remove the lid and return to the oven uncovered for an additional 30 minutes to reduce the sauce and further tenderize the meat.

5-Final Step: Remove the lamb shanks and keep them warm. Discard the bay leaves and thyme sprigs, then strain the sauce by pressing the vegetables to extract juices. Return the liquid to the pot and simmer to reduce it to a syrupy consistency if needed, adjusting seasoning as required. Serve the lamb shanks with the sauce over mashed potatoes, polenta, or pasta, garnished with fresh thyme leaves.