Melt butter in microwave or pan and use a brush to put on ciabatta rolls.
Sprinkle garlic and chopped basil on rolls.
Place in broiler 3-4 minutes until lightly toasted, top with mozzarella and allow to melt slightly. *While this is heating, heat leftover steak. If cooking steak fresh, start earlier and allow to rest while bread toasts*.
Take rolls out of broiler and top with sliced steak and tomato slice.