Heat a little oil in a large saucepan or casserole dish over a medium heat.
Add the onion and cook for about 5 minutes until softened.
Stir in the garlic and cook for 1 minute, then add the carrot and red pepper. Cook for a further 3 minutes, stirring occasionally.
Add the tomato purée, chipotle paste, cumin, oregano and smoked paprika. Stir for 1 minute until the vegetables are coated in the spices.
Add the potatoes and stir well to coat them in the tomato and spice mixture.
Pour in the chopped tomatoes and enough beef stock to cover the vegetables generously.
Bring to the boil, then reduce the heat and simmer for about 15 minutes, or until the potatoes are almost tender.
Stir in the black beans and green beans. Continue cooking for 5 minutes, or until the vegetables are tender.
Add the chopped roast beef and cook for a further 2–3 minutes, just until heated through. The stew should be thick and hearty.
Taste and adjust the seasoning if needed.
Serve topped with chopped parsley or coriander and a squeeze of lime juice. A spoonful of sour cream can also be added if desired.