Heat oil in a kadai or pan. Add the sliced onions, mix well and fry for a minute on medium heat.
Add the mutton pieces, mix well and stir for a minute on medium heat.
Add the ginger garlic paste, mix well and fry for a minute.
Add the sliced tomatoes, salt and turmeric powder. Mix well and fry on medium for a minute.
Now reduce heat to low and cover & cook on low heat for around 15 mins till the onions & tomatoes have softened. Open the lid and give a stir in between.
Now add 250 ml water, give a mix and cover & cook on low heat for around 40 mins till the mutton pieces are tender. (Alternatively you can also transfer it to a pressure cooker and pressure cook for 4 whistles till the mutton is tender.)
Once the mutton pieces are tender, lower heat and add the whisked curd/yogurt.
Mix it well and cook on low heat for around 4-5 mins till it is cooked and oil separates.
Add 3 tsp of the karahi masala that was made earlier and mix it well.
Now add the chopped green chillies and ginger juliennes, mix and cook for 5 mins on low heat. You can add little water if required.
Add the roasted, powdered Kasuri Methi, mix it well and simmer for 2-3 mins. Garnish with chopped coriander leaves.