Moo Dang, literally means 'red pork'. Because the pork you see hanging in restaurants is always obscenely red, for a long time I thought that you had to add red food coloring to make the barbequed pork. Well, I found out that you don't have to. The pork will turn red when cooked, just not the fire engine red seen in restaurants.
In Thailand, Moo Dang is traditionally made by boiling pork in the marinade, but I have an aversion to boiling foods because of the loss of flavor and nutrients. That may be why you see a lot of restaurants adding the food coloring.