1. Clean fish and make 3-4 deep cuts on each side.
2. Hang yogurt in a muslin cloth for 2 hours to remove whey.
3. Mix yogurt with cream, ginger and garlic pastes, carom seeds, gram flour, white pepper, red chilli and cumin powders, lemon juice, salt and turmeric.
4. Rub mixture on both sides of the fish.
5. Set aside for 2 hours.
6. Skewer fish from mouth to tail and roast in a hot tandoor or grill for 6 minutes or in a preheated oven at 350 ºF for 10 minutes.
7. Remove from oven. Hang skewers for 5-7 minutes to let excess moisture drip off.
8. Baste with oil and roast again for 5 minutes.
9. Serve with mint chutney and onion rings.