Season the goat meat with salt and pepper.
Heat the oil in a heavy pan over medium heat. Add the cinnamon stick, cardamom, cloves and bay leaves; cook until spices sizzle, about 30 seconds. Stir in the goat meat, increase the heat to medium high and cook until the meat begins to brown and its natural juices have evaporated.
Add the onion, garlic and ginger. Cook, stirring frequently, for 4-5 minutes. Stir in the tomato paste, turmeric, coriander, cumin and goat masala. Cook, stirring constantly for 2- 3 minutes.
Reduce the heat to low and then add the warm water, stirring and scraping up any accumulated browned bits from the bottom of the pan. Cover and simmer for 40 minutes or until the meat is tender. Stir frequently to make the sauce does not stick at the bottom of the pan and add more water as needed.
Add the potato and cook until potato is tender, about 15 minutes. Uncover and continue to simmer until preferred sauce consistency has been reached. Season to taste with salt and pepper. Stir in the fresh mint and cilantro leaves.
Serve with rice or nan. Drizzle with fresh lemon juice, if using.