The sauce was a little too thin and brown to be just soy, maybe had some fish sauce added? birds eye chilies sounds promising although some of the pieces looked bigger, lemon grass maybe? Dont know about chicken rice balls. They just had a tupperware of rice and would grab a small handfull, put it on a napkin pinch a bit off and sort of squeeze it lightly into a ball, dip it lightly into the sauce, not all the way in. Looked like plain rice, although quite dry and very sticky