Grind the ginger and garlic with little water to make a smooth paste. Add this ginger-garlic paste, chopped onions red chili powder, turmeric powder and 1 tsp of salt to the lamb pieces. Mix well. Add 2 cups of water and pressure-cook until the lamb is tender. Grind the grated coconut with tomatoes and 3 cups of water to make a smooth paste. Set aside. Heat the oil in a pan and fry the cinnamon and bay leaves for a minute. Then add the potatoes and fry for few minutes. Add little water and cook until the potatoes are 3/4 cooked. Now add the pressure-cooked meat with its spice gravy and stir-fry foe few more minutes. Then add the coconut-tomato paste and bring it to a boil. Cover the pan and let it cook over medium heat for 15-20 minutes or until the raw smell of coconut is gone. Add some salt if needed. Sprinkle with chopped coriander leaves. Serve hot.