Heat oil in a medium saucepan over a medium heat. Add onion and cook for 5 minutes until softened, but not browned. Add the sweet potato and garlic and cook for 5 minutes, stirring occasionally. Stir in the spices and cook for 30 seconds until aromatic. Add tomatoes, chickpeas, mandarin peel, salt and stock. Bring to the boil then reduce heat to a low simmer and cook for 20 minutes, or until sweet potato is cooked through.
Stir in the spinach leaves. Cook for about 3 minutes until leaves have wilted. Stir through the mandarin juice.
Garnish with coriander leaves. Serve with warmed roti bread.