Marinate chicken with curd, ginger-garlic paste, turmeric, chili, and salt; set aside for 15–20 mins.
Dry roast and grind coriander, cumin, fennel, peppercorns, and dry red chillies to make karahi masala.
Heat mustard oil in a kadai, add bay leaf, cinnamon, cumin, and peppercorns.
Sauté chopped onion until golden, then add ginger-garlic paste and dry spices.
Add tomato puree and cook until oil separates.
Mix in marinated chicken and cook until tender and flavorful.
Add capsicum, pearl onions, and whole red chillies; cook for 5 more minutes.
Finish with butter, ghee, kasuri methi, garam masala, and fresh coriander.