Add the onions, garlic, oregano, cumin and paprika to the pan with a splash of water. Add a good pinch of salt and cook for 5 minutes.
Stir in the tomato paste, chipotle peppers, adobo sauce, mustard, vinegar, sugar and chilli flakes and cook for 2 minutes.
Stir in the barbecue sauce then the ale and stock and bring to the boil.
Pour the contents of the pan over the beef cheeks.
Cover the dish tightly with tinfoil or a lid and braise for 3 hours or until very tender. Remove the lid and cook for another 30 minutes before serving.