Mix in grounded spices, stir for few seconds, then mix in mutton pieces. Cook on medium heat for another 5 minutes until the meat has changed its color.
Next, pour 2 cups of water in the pot. Close the pot with a tight lid and cook on medium heat for 45 minutes until meat is very soft and coming off the bones. ( You can pressure cook too.)
Dry roast wheat flour on medium heat with constant stirring. Remove flour from heat. Mix wheat flour with 1 cup of water to form a slurry without any lumps. Set aside.
When the meat is cooked add wheat flour slurry and yogurt to it. Mix well and add 1 cup of water (less or more as needed for desired consistency). Cook for another 5-7 minutes until oil separates.
Add butter in the last and simmer for 1 minute. Garnish with ginger and serve with hot naan and lemon wedges.