Special Equipment: butchers twine
Preheat grill medium (about 400°F). In a bowl toss peppers, onion and tomato in olive oil and barbecue seasoning. On a lightly greased grill, grill vegetables until charred all over and tender, about 4 to 6 minutes. Remove from grill and peel away any loose skin from the peppers and tomato. Slice peppers, tomato and onion into 1-inch pieces and place in a large bowl, adding the sliced mango. Set aside.
Place the banana leaf squares onto the grill for a 2 to 3 seconds per side, until just warmed through and the leaf turns bright green. This will make the banana leaf more flexible and easier to work with.
Season the fish with salt and place a bit of butter onto each fillet. Gently rub the butter into the fish. Centre the bass fillet, skin side down, onto a banana leaf square. Place some of the sliced mango and grilled vegetable mixture over top the fish. Shingle the sliced scallops over top the vegetable layer and season with salt and pepper. Add a sprig of fresh cilantro and a drizzle of beer. Roll each banana leaf into a tight little package like you were making a burrito, securing with butchers twine.
Place banana leaf packages onto preheated grill and grill-bake over indirect heat, with the lid closed for about 15 to 20 minutes. If the pouches start to burn, use a little more beer or water to add some moisture.
Remove banana leaf pouches from grill. Using a knife cut off the butchers twine and peel back the banana leaf. Serve immediately in banana leaf pouch.
Tip: If you cant find banana leaf, you can use aluminum foil instead to make the pouches. Dont eat the banana leaf or the foil.