In a pan, heat oil and add the whole spices: black peppercorns, cumin seeds, cinnamon sticks, and green cardamom. Let them sizzle until aromatic.
Add ginger-garlic paste and sauté until it turns light golden.
Mix in red chili powder, turmeric, and coriander powder. Cook for a minute to remove the raw spice flavor.
Add the marinated chicken and cook on high heat until it changes color and releases moisture.
Stir in the crushed brown onions, mix well, and add a little water.
Cover and cook on medium heat for about 20 minutes, or until the chicken becomes tender.