Heat the oil in a large frying pan or casserole. Peel and finely chop the onion and add to the pan. Fry over a gentle heat.
Whilst it is cooking, peel and finely chop the carrot and add to the pan.
Add the garlic and paprika. Cook over a medium heat for 2 minutes.
Drain and rinse the butterbeans and add to the pan, then add the tinned tomatoes.
Refill the empty tomato tin half way with water, and add to the pan, along with the tomato purée, sugar and dried oregano. Season well with salt and black pepper, bring to the boil, then reduce to a simmer and cook for 12-14 minutes until the sauce is thick. If the beans starts to get a little dry, add a splash of water and/or cover with a lid.
Roughly chop the parsley and mint and stir through the stew just before serving. Taste and adjust seasoning if required, then serve alongside crusty bread and a crisp green salad.