Heat oil, on medium heat, add cinnamon stick, black elachie, star aniseed and bay leaf. Fry for a few seconds until it is fragrant. Add onion and curry leaf.
Once onion is golden brown, add the ginger/garlic paste. Saute for a minute.
Add masala, turmeric, cumin powder, coriander powder, fennel powders and garam masala and fry for a further minute. It will form a nice thick paste. Add a few drops of hot water to prevent burning.
Add the tomato and cook for 5 minutes, when the oil surfaces to the top you wil know that it's cooked.
Add the lamb and mix well. Season with salt. Cover and cook for 30-45 minutes or until the liquid has reduced.
Add the potatoes, cover and cook for 5 minutes on medium to low heat. Do not add water, unless it's really dry. Add 1 cup of hot water, cover and simmer on a low heat until the potatoes are tender, should take about 1 to 1&1/2 hours. You can add more water depending on how thick a gravy you require. If you're living at high altitude you may need more water than others. Garnish with coriander.