Cut the meat into bite-size pieces,toss in olive oil,oregano,sea salt and pepper,before marinating for three hours.
Whiz the yoghurt,tahini,cumin,parsley,coriander,lemon juice,sea salt and pepper in a blender. Thin out with water if too thick,and refrigerate.
Heat the barbecue or flat grill. Cut the zucchini into two-centimetre rounds and skewer alternately with cherry tomatoes on four long metal skewers. Thread the meat on another four metal skewers,and brush with olive oil. Grill the skewers for three to four minutes or until well-marked,then turn and cook for a minute or two to your liking.
Serve on grilled flat bread with green tahini and lemon.