Preheat your oven to 160°C (320°F). Season the lamb shanks generously with salt and pepper. Heat olive oil in your ovenproof skillet or Dutch oven over medium-high heat until shimmering. Sear the shanks until deeply browned on all sides, about 4-5 minutes per side, until a rich caramel color develops. Use tongs to turn them carefully, ensuring even searing. Remove the shanks and set aside.
Add diced onions to the same pan. Cook over medium heat, stirring occasionally, until the onions are golden and fragrant, about 8 minutes. The onions should be soft and translucent, with a sweet aroma filling the kitchen. Add minced garlic and cook for another minute until fragrant.
Pour in the red wine and bring to a boil. Use a wooden spoon to scrape up all the browned bits from the bottom of the pan—this adds flavor. Let the wine simmer until it has reduced by half, about 5 minutes, until it becomes syrupy and fragrant.
Add the sprigs of thyme and bay leaf to the pan. Return the seared lamb shanks to the skillet, nestling them into the aromatic sauce. Pour in the stock, enough to come halfway up the sides of the meat. Bring the liquid to a gentle simmer.
Cover the skillet tightly with a lid or foil. Transfer it to the preheated oven and braise for about 2.5 to 3 hours. The meat should become very tender, falling off the bone easily. Check halfway through and add a splash more stock if the liquid reduces too much.
Once the lamb is tender, carefully remove the shanks from the pan and let them rest on a plate. Meanwhile, place the skillet back on the stove over medium heat. Uncover and simmer the sauce to reduce it into a glossy, velvety glaze, about 10 minutes. Taste and adjust seasoning if needed.
Strain the sauce through a fine sieve if you prefer a smooth finish, or leave the herbs in for added aroma. Spoon the sauce generously over the lamb shanks. Garnish with fresh herbs if desired.
Serve hot with crusty bread or mashed potatoes to soak up the rich wine sauce. Enjoy the tender, flavorful meat and the fragrant, velvety gravy that makes this dish truly special.
