Preheat the oven to 200°C fan. Place the aubergine, sweet potato, red onion and carrots on a tray, drizzle with olive oil, season with salt and toss to coat.
Roast for around 25 minutes until starting to soften and take on colour.
Remove the tray from the oven and stir in the chickpeas.
Stir in the tagine paste along with the tomato purée and a small spoon of harissa. Add a splash of water or stock and return to the oven for a further 10 to 15 minutes until the vegetables are coated in a rich, slightly reduced sauce.
Stir through chopped coriander.
Finish with a squeeze of lemon juice before serving.