In a small saucepan, bring 2 cups of water to a boil. Cut an "x" in the bottom of the tomatoes. Place the tomatoes in the boiling water and boil for 5 minutes. Remove the tomatoes from the pot and reserve the water. When tomatoes are cool enough to handle, remove and discard the skins.
On a dry comal, griddle or in a cast-iron frying pan, toast the chiles until they give off their aroma. Place in a bowl and cover with reserved tomato water. Soak for 20 minutes. Remove chiles from the water. Reserve the water.
On the same comal, roast the onion and garlic for 8 to 10 minutes over medium heat or until transparent.
Place the chiles, tomatoes, onion, garlic, oregano, allspice, peppercorns, vinegar, and Worcestershire sauce in a blender. Blend well with 1/2 cup chile soaking water. Pour through a strainer to remove the skins.
In a medium frying pan, heat the butter and oil. Pour in the chile mixture add the bay leaf. Fry for 5 minutes. Add salt.
Holding the banana leaves with tongs, pass the leaves over a gas flame to soften them. If you don't have a flame handy, you can boil them until soft, about 20 minutes, covered. Remove and set aside.
Heat a long griddle that covers 2 burners until very hot. Open the fish so it is lying flat, skin side down.
Cut a piece of heavy-duty aluminum foil twice the size of the fish. Totally butter one half of the foil. Place the banana leaf on the buttered portion of the foil. Lay the fish skin side down, on top of the leaf. Sprinkle salt and pepper over the fish. Spoon 1/4 cup of the salsa del diablo over the fish. Sprinkle the Worcestershire and Maggi sauce over the fish, including the head. Dot butter over the fish. Add the tomato and onion slices. Add the bay leaves and parsley. Cover the fish with the banana leaf. Pull the foil over the top of the fish and seal by folding over the edges. It is important to have a good seal on all 3 edges, so the steam does not escape during cooking process. Carefully move fish over to the grill and cook for 10 minutes. The foil should fully puff up in the process. Watch the foil to make sure that the steam is not escaping. If it is, reseal the fish. Serve immediately with totadas or totopos.