Preheat the barbecue or grill to medium. Make the salsa: 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 the garlic and brush onto the steaks and courgette slices. Cook the steak and courgettes for 2 minutes each side (or cook the steak longer to your liking) 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.