Preheat oven to 400 deg F. Wash and pat fish dry. Sprinkle 1 t salt inside and set aside. Blend garlic, chili, ginger, 1/2 the coriander, coriander seeds, brown sugar, turmeric, mustard seeds, fenugreek seeds, salt and lemon juice until it all becomes a smooth paste (Add some water if needed). Fry onions until they are soft and golden brown. Add the blended Masala and cook until most of the liquid is gone, and it starts to leave the sides of the pan. Add the tomatoes and Garam Masala. Fry for 2 minutes more and remove. Coat one side of fish, stuff 1 1/2 cups inside. Close opening, spread the rest of the Masala over it. Cover tightly and bake for about 25 minutes. Grill for 1-2 minutes in the broiler, and sprinkle on the remaining coriander. Serve.