I love the flavours of this Mexican-style dish. Chipotles, or smoked jalapeno chillies, give a wonderfully earthy, smoky quality to the meat. You can buy them at good European delis, either in a can or jar with tomato sauce, which I prefer for this recipe, or as dried loose chillies. Using beef ribs is really cost effective – you can shred the leftovers and freeze the meat with the extra sauce, then use it to put together a tasty nacho-style sauce.