Heat the oil and ghee in a large pot over medium heat. Cook the cumin seeds in the oil until the seeds begin to change color.
Stir in chopped onion onion; cook and stir until onion has softened and turned translucent, about 5 minutes. Add the garlic and ginger; continue cooking until the onions brown, about 5 minutes more.
Mix in the chopped tomato, tomato paste, garam masala, turmeric, salt, serrano pepper, and water; simmer 5 minutes. Lay the chicken into the sauce; mix gently to coat the legs. Cover pan and reduce heat to medium-low. Cook until chicken is no longer pink near the bone, about 40 minutes. Garnish with cilantro to serve.