01 - Pat the lamb shanks thoroughly dry with paper towels and season generously with salt and pepper on all sides.
02 - Heat the vegetable oil in a large heavy-based pot or Dutch oven over medium-high heat. Sear the lamb shanks on all sides until deeply browned, approximately 3-4 minutes per side. Remove from pot and set aside.
03 - In the same pot, add the sliced onions and sauté until golden brown and caramelized, about 10 minutes. Stir frequently to prevent burning.
04 - Add the minced garlic and grated ginger to the pot. Cook for 1-2 minutes until fragrant, stirring constantly to prevent sticking.
05 - Stir in all ground spices (coriander, cumin, garam masala, turmeric, chili powder, black pepper) plus whole spices (bay leaves, cloves, cardamom pods, cinnamon stick). Toast for 1 minute, stirring constantly to release their aromatic oils.
06 - Add the canned chopped tomatoes to the pot and cook for 5 minutes, allowing them to break down and release their juices into the spice mixture.
07 - Return the browned lamb shanks to the pot. Pour in the stock and bring to a gentle simmer. Cover with a tight-fitting lid, reduce heat to low, and cook gently for 2.5 hours. Turn the shanks occasionally to ensure even cooking.
08 - Stir in the yogurt, fresh chopped tomatoes, and green chili. Simmer uncovered for another 45-60 minutes until the lamb is fall-off-the-bone tender and the sauce has thickened to a rich consistency.
09 - Skim any excess fat from the surface if desired. Taste and adjust seasoning with additional salt if needed.
10 - Garnish generously with fresh chopped cilantro and serve immediately with lemon wedges alongside steamed basmati rice or naan bread.