Set the slow cooker to low. Heat 1½ tbsp oil in a large, non-stick pan over a high heat and fry the mince for 10-12 mins or until evenly browned. Tip into the slow cooker.

Heat the remaining oil in the pan. Fry the onion, celery and pepper for 10 mins or until softened. Add the garlic, cumin and paprika and fry for 1 min. Tip into the slow cooker.

Stir in the oregano, chipotle paste, tomato purée, tomatoes and stock. Season. Cover and cook for 6-8 hrs.

Stir in the beans and chocolate during the final 30 mins of cooking. Serve with a bowl of rice or tortilla chips and a dollop of soured cream.