Wash and pat dry the mutton pieces. Marinate the mutton with ½ tbsp ginger paste, 1 tsp garlic paste, a little turmeric powder, chilli powder, lemon juice and 1 tbsp mustard oil. Refrigerate for at least 3-4 hours, the more the merrier.
Marinate the potato halves with a little turmeric powder and salt. Heat 1 tbsp oil and fry the potatoes till golden. Keep aside.
Add the remaining oil to the same pan, add the sugar, when the sugar starts to caramelize, throw in the bay leaves, crushed green and black cardamom, cloves and cinnamon. When the spices start to release their aroma, add the sliced onions, cook over a medium flame till the onions turns golden brown.
Add the tomato puree, cook till the tomatoes are cooked and the raw smell of tomatoes is gone. Add the remaining ginger-garlic paste, cook for 3-4 minutes.
Now add the mutton along with the marinade, sprinkle in the the remaining turmeric powder, special spice powder and a little salt.
Cook over a low flame, while stirring occasionally, till oil starts to separate from the masala. Add 3 cups of warm water, bring the curry to a gentle boil.
Throw in the fried potatoes, continue to cook over a low flame till the mutton is tender. (The the curry shall be of a pouring consistency, neither too thick, nor too thin.) If needed, add a splash of warm water to get the consistency right.
Adjust seasonings. Finish with a sprinkle of garam masala. Serve hot with plain rice.