Pressure cook the mutton along with cinnamon, cardamoms and salt in 3 cups water for 20-25 minutes on a low flame after the first whistle.
Heat oil in a pan and saute the onion till light brown. Now add the ginger-garlic paste and all the dry spices mixed with some water. Stir fry for a few seconds.
Add the tomato puree and the roasted oats. Mix well and simmer for a minute. Add the mutton along with the stock.
Bring it to a boil and simmer for 5-10 minutes or till the soup thickens to a desired consistency. Garnish with coriander leaves and serve as a light meal or enjoy whenever you wish.