Bengali Mutton Kassa

Cook the mutton (Koshano process)

• Lower the heat and add the remaining turmeric powder, red chili powder, cumin powder, and coriander powder. Stir for 30 seconds.
• Add the marinated mutton to the pan. Increase the heat to medium-high and begin the 'koshano' (slow sautéing) process.
• Sauté the mutton for 20-25 minutes, stirring continuously. The mutton will release its juices; continue cooking until the liquid evaporates and oil begins to separate from the masala.
• Stir in the tomato puree and slit green chilies. Continue to cook for another 8-10 minutes until the oil separates again.

Slow cook to finish

• Return the fried potatoes to the pan and add the remaining 0.5 tsp of salt.
• Pour in 2 cups of hot water and stir everything together. Bring the curry to a boil.
• Once boiling, reduce the heat to low, cover the pan with a tight-fitting lid, and let it simmer for about 70-80 minutes, or until the mutton is fork-tender.
• Check and stir every 15 minutes to prevent it from sticking to the bottom. Add more hot water if the gravy becomes too thick.

Garnish and serve

• Once the mutton is cooked, stir in the garam masala powder and ghee.
• Turn off the heat, cover the pan, and let it rest for 10 minutes for the flavors to meld.
• Garnish with freshly chopped coriander leaves and serve hot.