Heat oil in a pressure cooker, add green cardamoms, black cardamoms, cloves, bay leaves and cinnamon and sauté for half a minute. Add onions and sauté till golden brown.Add mutton and sauté on high heat for five minutes. Add garlic paste and sauté for two minutes.
Add yogurt, turmeric powder, red chilli powder, salt and coriander powder and cook for two minutes, stirring continuously.Add tomato puree and green chilli and stir.
Add six to seven cups water and bring to a boil. Close the lid and cook under pressure until the pressure is released five to six times (5-6 whistles).
Open the lid when the pressure is reduced completely. Add aram masala powder, crushed peppercorns, coriander leaves and mint leaves and cook for a few minutes or till most of the water is absorbed. Serve hot with rotis.