1Heat 2 tbsp of olive oil in a saucepan over a medium heat. Add the onion and cook, stirring occasionally, for 5-6 minutes until a little golden.
2Add the beef and a large pinch of salt and pepper. Mix well and cook, stirring occasionally, for 4-5 minutes until browned. Add the garlic and cook, stirring occasionally, for about a minute until fragrant.
3Add cumin, paprika, tomatoes, tomato puree, chickpeas, harissa, stock pot, water, and salt. Mix well and bring to a boil.
4Cover, reduce heat to low, and simmer for 1 hour. Remove the lid, increase heat slightly, and cook, stirring occasionally, for 30-40 minutes until rich and thick.
5Preheat the oven to 200°C fan. Rub 1 tbsp of olive oil over the sweet potatoes and place them in a roasting tin. Season with salt and pepper and roast for 1 hour or until tender.
6Load the roasted sweet potatoes with the harissa chilli and top with a dollop of sour cream to serve.