Preheat the oven to 200C.
Chop the veggies into 2-3cm cubes, then add them to a baking tin with the tomato paste, oil, vegetable stock, spices, 1/2 tsp salt & black pepper. Stir until the veggies are evenly coated, then bake for 30 minutes, giving the veggies a stir halfway through.
In the meantime, toss the chickpeas in harissa. Add the chickpeas on top of the roast vegetables and bake for another 15 minutes.
Cook the cous cous according to packet instructions, drain & toss in with the roasted vegetables & chickpeas.
Combine the tahini with 2 tsp lemon juice and a pinch of salt. Whisk to combine, add 1-2 tsp water and continue to whisk until the dressing has the same consistency as honey.
To serve, drizzle the tahini dressing over the couscous, squeeze over with lemon & top with the chopped parsley