Preheat the oven to 450 degrees F.
Carefully score the fish in a diamond pattern using a sharp knife, making sure not to cut through the flesh entirely.
Lay the banana leaf across the center of a large roasting pan or casserole so that the excess falls over either side of the pan. Place a third each of the cilantro, onions and jalapenos on top. Sprinkle the inside of the fish with salt, 1 tablespoon of the olive oil and a handful of onion slices. Lay the fish on the onion bed and top with the remaining cilantro, onions, jalapenos, olive oil, the jalapeno juice and lime juice. Wrap the excess banana leaf over the fish and tuck under to close. Cover the entire roasting pan with foil.
Cook the fish in the oven until a skewer inserted into the fish meets no resistance, 45 minutes. Unwrap the banana leaf and serve family-style with the Mango Salsa. Pass around warm tortillas to fill with snapper and salsa, if using.
This recipe was provided by a chef, restaurant or culinary professional and may have been scaled down from a bulk recipe. The Food Network Kitchens chefs have not tested this recipe, in the proportions indicated, and therefore, we cannot make any representation as to the results.
Toss together the lime juice, mango, onion, bell peppers and chiles in a medium mixing bowl. Taste and adjust the seasoning with salt and more lime juice as needed.