Heat the oil in a large saucepan over a low-medium heat and fry the carrots, celery, onions and mixed herbs for 10-12 mins, stirring occasionally until the veg is soft but not golden. You may need to add a splash of water if the veg starts to catch.

Stir in the garlic and both peppers, and cook for a further 5 mins until the peppers begin to soften. Sprinkle in the chilli powder and paprika, turn up the heat to medium, then stir and cook for 1 min. Mix in the tomato purée and cook for a further 1 min, then pour in all of the beans, the tomatoes and stock.

Stir well, bring to the boil, then reduce the heat to a simmer. Cook for 25-35 mins until the beans are tender and the sauce has thickened. Serve with rice, grated cheddar and soured cream, if you like.