Remove the halloumi cheese from the packet. Drain off water and pat it dry using kitchen paper. Slice into bite-sized cubes and put into a mixing bowl. Halve and de-seed the peppers and cut into bite-sized pieces. Peel the onions and cut each one into six wedges. Add the vegetables to the bowl with the harissa paste and garlic. Stir in the olive oil, combining everything thoroughly and leave to marinate for at least 15 minutes. To make a sauce, prepare the the cucumber by peeling, halving and de-seeding it first. Then chop the flesh. Add the yogurt, mint and seasoning, stirring until it has fully combined. Cover and put into the refrigerator until ready to serve. Thread the cheese and vegetables onto four skewers and grill under a medium hot heat, turning occasionally, for 8 minutes, or until peppers begin to char. Serve with the sauce.
