In a medium enameled cast-iron casserole, heat the oil until shimmering. Add the onion and curry leaves and cook over moderate heat until lightly browned, about 7 minutes. Add the garlic and ginger and cook until fragrant, 1 minute. Stir in the dissolved tomato paste along with the coriander, garam masala, cayenne, turmeric, dried chiles, star anise and cinnamon sticks. Add the ribs, season with salt and stir until coated with spices. Cover partially and cook over very low heat until the meat is tender, about 1 hour and 30 minutes. Spoon off as much fat as possible and discard the star anise, cinnamon sticks and bay leaves, if using.