Peel and finely chop the onion. Chop the celery and crush the garlic.
Heat the oil in a large casserole and add the onion and celery and fry gently for 5-10 minutes. Add the garlic, chipotle, spices and oregano and fry for a minute more.
Add the pearl barley and tomatoes plus 1 can of water and season well. Bring to the boil then reduce to a simmer, cover and cook for 45 minutes or until the pearl barley is tender.
Meanwhile, drain and rinse the kidney beans and black beans and set aside. Add the beans, cocoa powder and vinegar and bubble for 10 minutes until the beans are piping hot.
Serve with fresh coriander leaves, soured cream, cheese, lime wedges and tortilla chips.