Place a large pan on a medium-low heat and add 2 tablespoons of olive oil. Peel and finely chop the onion, and deseed and chop the pepper. Add the chopped veg to the pan, along with the chilli powder, cumin and smoked paprika. Stir and cook until soft, around 15 minutes. Meanwhile, peel and chop the sweet potatoes into bite-sized chunks, and add to the pan, along with the chopped tomatoes, a tin’s worth of water, the kidney beans (juices and all), and tomato and garlic purées. Stir everything together, then bring to the boil and simmer gently until the sweet potato has softened, but still holds its shape, and the sauce has thickened – around 30 minutes. Season to taste with a tiny pinch of sea salt and black pepper. Delicious served with fluffy rice or taco shells, guacamole, grated cheese and a sprinkling of finely chopped fresh chilli and spring onion.