In a small bowl, mix the ground cumin, ground coriander, turmeric, paprika (or Kashmiri chili powder), and garam masala. Set aside.

In a large, heavy-bottomed pot, heat the vegetable oil over medium-high heat. Add the lamb chunks in batches, searing on all sides until browned. Remove the lamb from the pot and set aside.

In the same pot, add the sliced onions and cook for about 5-7 minutes, stirring occasionally until softened and golden. Add the minced garlic, grated ginger, and green chilies (if using) and cook for another 1-2 minutes until fragrant.

Add the prepared spice mix, cinnamon stick, cardamom pods, and cloves to the pot. Cook for 1-2 minutes, stirring constantly to bloom the spices and release their aromas.

Stir in the tomato paste, then add the canned chopped tomatoes. Cook for 5 minutes until the tomatoes start to break down and the sauce thickens slightly.

Return the seared lamb to the pot, stirring well to coat it with the sauce. Season with salt and freshly ground black pepper. Add a splash of water if the sauce seems too thick. Cover and reduce the heat to low, letting it simmer for 1.5 to 2 hours, or until the lamb is tender and the flavors are well combined.

Once the lamb is tender, remove the pot from the heat and stir in the yogurt for a creamy, slightly tangy finish. Adjust seasoning if needed.

Garnish the Lamb Rogan Josh with fresh coriander and serve hot with basmati rice, naan, or roti.