Make a fine paste with half of vegetable oil, garlic, coriander, ginger, red chili powder, cumin powder, garam masala, lime juice and zest, and salt. Heat the remaining oil in a pan and add the gram flour, stirring to make a paste, and cook for about a minute till fragrant and lightly coloured. Add the mixture to the spice paste and combine with the yogurt. Mix well all the ingredients for the marinade. Wash the fish and cut them into cubes. Gently rub the marinade over the fish pieces and marinate for an hour. Pre-heat the oven to 200 degree Celsius and spread out the marinated fish in a baking dish. Cook for 10-15 minutes on the top rack turning the fish pieces once. Baste once or twice during cooking. Serve hot with chutney or sauce.