Season the lamb shanks with black pepper. In a large cast iron pot, heat the vegetable oil on high heat. Brown the lamb shanks in batches, make sure all sides have been sealed, and keep them on the side.
In the same pot add a couple of tablespoons of vegetable oil, chopped onion, cinnamon stick, and bay leaf; sauté the onions until they have softened and have a translucent colour. Add the green chiles and the garlic and cook for another 2 minutes, stirring often.
Return the meat and any juices to the pot, add the coriander, cardamom, tomato paste, and some salt, and mix well. Let this cook for a minute, then add the chopped tomatoes and beef stock. Bring to a gentle simmer and taste for salt. Cover the pot and cook for at least 90 minutes, or until the meat has softened.
Thaw the frozen okra for about 15 minutes. In a shallow frying pot, heat up vegetable oil for frying. Deep fry the baby okra for about 8-10 minutes on medium heat until slightly crispy and light golden brown. Set aside until use. Deep fry the garlic cloves and keep them to the side.
When the meat is tender, add the fried okra, fried garlic, and lemon juice. Simmer for about 15 more minutes and season with black pepper to taste. Serve with rice.