Nam pang in Cambodia is not necessarily eaten as a sandwich. In market stalls it will be served separately with a platter of of the various meats as well as shredded green papaya, carrots, tomato and cucumber. It's more of a do-it-yourself deal and comes with a selection of great spicy condiments. I find these to be a much better deal than the pre-made versions you get in Phnom Penh, but communication can be a problem as the owners aren't use to dealing with foreigners.