Heat ghee or oil in a large pan over medium heat. Add cumin seeds, cinnamon stick, cardamom pods, and bay leaves; sauté until fragrant.
Add chopped onions, garlic, and ginger. Cook until onions are soft and golden brown.
Stir in green chilies, ground coriander, cumin, turmeric, cloves, salt, and black pepper. Cook for 2 minutes.
Add lamb chunks and brown on all sides, stirring frequently.
Mix in chopped tomatoes, tomato puree, and lamb stock. Bring to a boil, then reduce heat.
Cover and simmer gently for about 1 hour, stirring occasionally, until lamb is tender and sauce thickens.
Add chopped red bell pepper in the last 15 minutes of cooking.
Adjust seasoning as needed and serve hot.