Sauté the Onions: Heat oil in a large pot. Add cumin seeds and sliced onions. Sauté until golden brown.
Add Mutton & Aromatics: Add the mutton along with garlic and ginger paste. Cook for 5–6 minutes until browned and fragrant.
Spices &Tomatoes: Add red chilli powder, turmeric, coriander powder, and salt. Stir well, then add chopped/blended tomatoes. Cover and cook on medium heat for 10–15 minutes, stirring occasionally, until the oil separates from the masala.
Add Water & Cook Mutton: Pour in about 2 cups of water (or enough to cover the meat), bring to a boil, then cover and simmer on low heat for 40–50 minutes, or until the mutton is about 80% cooked. Use a pressure cooker to reduce time if preferred.
Add Potatoes: Add the potatoes and cook uncovered for another 15–20 minutes until they are soft and the curry has thickened to your liking.
Final Touches: Add garam masala and green chillies(if using). Simmer for 5 more minutes.
Garnish & Serve: Sprinkle with chopped coriander and serve withnaan, roti, or rice.