To begin, you want to build a rich foundation of flavor. Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Take 4 lamb shanks, approximately 1 kg (2.2 lbs) in total, and season them generously with salt and pepper. Brown each side of the lamb shanks in the skillet, which should take about 8-10 minutes in total. This step ensures that all the amazing flavors get locked in and provides a wonderful depth to the dish.
After browning the lamb shanks, set them aside. In the same skillet, add one large onion, finely chopped, and sauté for about 3-4 minutes until it becomes soft and translucent. Then, add three minced garlic cloves and continue to sauté for another minute until fragrant. This mixture will help elevate the flavors of your gravy and lamb.
Transfer the browned lamb shanks, sautéed onions, and garlic into your slow cooker. Add two medium carrots, roughly chopped, along with 400 ml (13.5 fl oz) of tomato passata. Pour in 500 ml (2 cups) of water, and add 2-3 sprigs each of fresh rosemary and thyme for an aromatic touch. Finally, add an onion gravy stock pot to enrich the flavors of the gravy. Cover the slow cooker with the lid, set it to low, and let it cook for 8 hours.
Once the cooking time is up, your lamb shanks should be beautifully tender and practically falling off the bone. You can decide how you want your gravy—either leave it chunky for a more rustic experience or blend it until smooth. To serve, place one lamb shank on each plate and ladle the rich gravy over it. This dish pairs wonderfully with creamy mashed potatoes, crusty bread, or even roasted vegetables, perfect for soaking up all that delicious gravy.