Sprinkle beef with lemon juice, salt and pepper. Marinate for 2 hours. Drain beef, save marinade. Heat ghee and saute beef until well browned. Remove from pan and set aside. Add onions and garlic, saute until onion is well browned. Add ginger, chili powder, turmeric and cumin. Cook for 2 minutes. Spoon in yogurt and cook for 4 minutes. Add cauliflower and stir to coat. Add enough beef stock to marinade to make 2 cups. Return beef to the pan and cook over low heat, covered, about 10 minutes. Stir in garam masala and cilantro. Simmer for 5 minutes and serve over rice.