Preheat the barbecue or grill to medium. Place the tomatoes, spring onions, dried herbs, chilli, vinegar and sugar in a bowl. Season with black pepper, mix well and set aside.
Combine the oil and garlic and brush on to the steaks and courgette slices. Cook for 2 minutes each side on the barbecue or under the grill.
Remove from the heat and allow the steak to rest for 1 minute. Grill the ciabatta on both sides, until golden. Slice the steak diagonally into bite-size pieces.
Layer the lettuce, steak, courgette and tomato salsa on four ciabatta halves, then add the onion and garlic dip. Top with the remaining bread and serve.