1. Halve the courgettes lengthways, then slice into thick chunks. Cut the onion into wedges and separate into pieces. Thread the halloumi, cherry tomatoes, courgettes and onion onto eight skewers that have been soaked in water. Cover and chill the kebabs until you are ready to cook.
2. Mix together the olive oil, lemon juice, thyme, mustard and seasoning.
3. Preheat the barbecue or grill and arrange the kebabs on the rack. Brush with the baste. Cook for 4-5 minutes, turning often, until the cheese begins to turn golden and the vegetables are just tender. Serve while still hot with warm pitta bread.