Heat the oil in a large pan or casserole on a medium heat. Fry the onion, celery and carrots for 10 mins until soft and golden, then add the peppers and fry for another 5 mins.
Stir in the garlic for a minute, then add the tomato purée, all the beans and chopped tomatoes, then swirl out the tomato cans with a splash of water and add to the pan with the stock cube, bay leaves, sugar and vinegar.
Season and simmer, uncovered, for 25 mins until the sauce reduces to coat the beans and the peppers are soft.
Leave to cool before storing in transportable containers.
Will keep in the fridge for 3 - 4 days or freeze in portions and defrost in the fridge overnight.