Heat oven to 200C/180C fan/gas 6. Put the sweet potato chunks in a roasting tin and drizzle over 1½ tbsp oil, 1 tsp smoked paprika and 1 tsp ground cumin. Give everything a good mix so that all the chunks are coated in spices, season with salt and pepper then roast for 25 mins until cooked.
Meanwhile, heat the remaining oil in a large saucepan over a medium heat. Add the onion, carrot and celery. Cook for 8-10 mins, stirring occasionally until soft then crush in the garlic and cook for 1 min more. Add the remaining dried spices and tomato puree. Give everything a good mix and cook for 1 min more.
Add the red pepper, chopped tomatoes and 200ml of water. Bring the chilli to a boil then simmer for 20 mins. Tip in the beans and cook for another 10 mins before adding the sweet potato. Season to taste then serve with lime wedges, guac, rice and coriander. Make ahead and freeze for up to 3 months.