In a large skillet over medium high heat, heat the oil.
When the pot is hot, sear the lamb pieces until browned, 1 to 2 minutes per side. Remove the meat from the pot and set aside.
In the same pot over medium heat, heat the oil. Add the cinnamon, star anise and cloves. Cook, stirring frequently, until spices are toasted and fragrant, about 1 minute.
Add the onions, green chilies, garlic, ginger, and curry leaves and cook, stirring, until onions are soft and slightly browned on the edges, 3 minutes.
Add the tomatoes and continue cooking, stirring, until soft and mushy, a few more minutes.
When the vegetables are soft and mushy, add the chili boh and sugar. Cook, stirring constantly, until the chili paste is thoroughly incorporated, 1 to 2 minutes.
Add the meat curry powder and stir to combine. Continue stirring for a few minutes until the aroma of the spices become fragrant.
Return the meat to the pot, and stir until completely coated in the mixture.
Add 2 cups of water, and stir to combine. Bring to a boil and simmer covered, stirring occasionaly, 15 minutes.
After simmering for 15 minutes, add the potatoes, making sure the pieces are properly submerged within the gravy. Cover and continue simmering, until the meat and potatoes are tender, 20 minutes.
When the potatoes are tender, add the coconut milk, and stir to combine. Simmer for another 5 minutes. Rinse off any coconut milk residue from the carton or can with ¼ cup water, and add into the pot.
In a small bowl, add the tamarind paste and remaining ¼ cup water, and mix well. Add the mixture to the pot.
Add the beef stock cube, salt and seasoning powder. Adjust seasonings to taste.
Garnish with the chopped cilantro. Serve hot with steaming white rice or flatbread.