Heat oil or ghee in a heavy-bottomed pan or kadhai over medium heat.
Add cumin seeds and allow them to splutter.
Add the finely chopped onions and sauté until golden brown and browned.
Stir in the ginger-garlic paste and slit green chilies, and cook for a couple of minutes until fragrant.
Add the tomato puree and cook until the oil starts to separate from the masala.
Now, add the coriander powder, garam masala, turmeric powder, red chili powder, and salt to taste. Mix well to combine.
Add the marinated chicken pieces along with any remaining marinade to the pan. Stir to coat the chicken in the masala.
Cover the pan and simmer the chicken curry over low heat for 20-25 minutes, stirring occasionally, or until the chicken is cooked through and tender. If the curry becomes too dry, add a splash of water as needed.
Once the chicken is cooked, garnish the curry with freshly chopped cilantro leaves.