Heat the grill. Place the peppers on the grill until the skins are charred then, using tongs, transfer them to a plastic bag to rest and peel them when cool.
Place the whole fillet on a utility platter, brush with melted butter, and season with salt and pepper. Sear filet on all sides on hot part of the grill. Move to indirect for medium rare. Alternatively you can sear the fillet in a pan with oven safe handles and transfer pan to a preheated 425 degree F oven for about 30 minutes to reach the same internal temperature. Allow meat to rest before slicing. (On the episode we skewered the beef tenderloins on the sterilized shafts of old golf clubs, grilled them on the skewer, and sliced servings right off the skewer. If you have a rotisserie skewer, you can do something similar.)
In the blender, combine the peeled peppers with the scallions, garlic, cilantro, and lime juice. Blend these until a smooth consistency is achieved then, with the blender running, pour the olive oil in a thin stream through the feed opening. Add salt and pepper, to taste.
Slice bread in half lengthwise, brush with oil, and season with garlic powder. Grill briefly, cut side down.
Serve slices of fillet with sauce spooned over or on the side with slices of the bread as an accompaniment.