Preheat the oven to 180°C. Chop your potatoes into chip shapes and add to a baking tray spray with low-calorie cooking spray. Cook for 45-50 minutes turning halfway through.
Spray a frying pan with low-calorie cooking spray and set on a medium heat. Add the onion and cook for 4 minutes. Add the lamb mince and continue to fry, browning on all sides.
Add the harissa paste, coriander, cumin, chilli and onion powders, paprika, and oregano and stir to coat mince. Season with salt and pepper and stir through chopped olives
To a mixing bowl add the tomato, cucumber and half of the chopped mint, toss together and leave to one side.
In a small bowl combine the yoghurt, lemon juice and remaining mint. Leave to one side.
Once the sweet potato fries are cooked, divide them between your serving plates. Top with the lamb mixture. Add a little of the cucumber and tomato mixture and drizzle over the yoghurt.
Crumble over the feta and serve.