Heat a griddle pan until smoking hot. Drizzle the ciabatta with olive oil and chargrill for 2-3 minutes on each side. Remove from the pan and set aside in a warm place.
Drizzle the leeks with olive oil and chargrill for 3-4 minutes, turning frequently. Remove from the pan and set aside to keep warm.
Rub the steak with olive oil and season well with salt and freshly ground black pepper. Place onto the griddle and cook for 2-3 minutes on each side, or until cooked to your liking. Remove from the pan and set aside to rest in a warm place.
Preheat the grill to medium.
Place the griddled ciabatta onto a baking sheet and top each slice with equal amounts of gorgonzola. Transfer to the grill and cook for 2-3 minutes, or until bubbling.
To serve, place one slice of the gorgonzola-topped ciabatta onto a serving plate and top with the griddled leeks. Cut the steak into slices and place on top of the leeks, then place the remaining piece of ciabatta on top.