In a large pan over medium heat, add a drizzle of olive oil and onions and cook for 5-6 minutes until brown and softened. Add the celery, carrot, dried apricots, moroccan spice mix, and harissa. Stir to combine and cook for 2-3 minutes.
Add the lentils, chickpea, tomatoes and vegetable stock. Bring to a boil, and then let it simmer for 20 minutes. Season to taste.
To make the yoghurt topping, mix the yoghurt, tahini, and garlic in a small bowl. Season with salt and pepper.
To serve, top the soup with coriander and a dollop of the yoghurt dressing.