Preheat the slow cooker if necessary; see the manufacturer's instructions. Heat the oil in a large frying pan, add the onion and fry for 5 minutes, stirring, until softened.
Stir in the pepper, sweetcorn, garlic and spices and cook for 1 minute. Add the pulses, tomatoes, stock, sugar and a little salt and pepper and bring to the boil.
Pour the mixture into the slow cooker pot, cover with the lid and cook on high for 2–3 hours or until cooked through. Spoon into bowls and serve with crème fraîche and cheese, or spoon on top of baked potatoes.