Preheat the oven to 220 C (200 Fan), Gas Mark 7. In a large bowl stir together the maple syrup, harissa paste, olive oil, garlic and salt. Add the carrots and toss together until evenly coated.
Tip into a roasting tin and spread out. Cover the tin with foil and roast for 20 minutes until tender, then remove the foil and roast for a further 10 minutes to caramalise.
if you are using the pistachio nuts grind them coarsely, then sprinkle over the carrots and serve straight away.