Deseed and half your peppers, then place them over the really hot coals before they reduce to grey ash and stop flaming. Cook until softened and blackened all over then remove from the heat, place in a bowl and cover.
While the coals are still hot but no longer flaming grill the steak, flipping it every 30 seconds, until it has a decent crust and is rare/medium rare. Set it on a plate to rest.
Peel away the skins from the peppers and slice. Season liberally and dress with olive oil.
Season the yoghurt and spread over warmed flatbread. Top with peppers, sliced steak and sprinkle with feta.