Hi, I remember this ingredient as a child but I've long forgotten it. It was in a place that specialized in serving Banh Cuon. They put out a small bowl of fish sauce just as in other typical Viet restaurants. Now the ingredient I'm trying to identify is a condiment that was on all the tables. It was a clear liquid in a small bottle with a dropper, and we would add some drops of it in our nuoc mam to help perfume it and lessen the "fishiness" of the nuoc mam. I THINK it's jasmine extract or something like it. Does anyone here know what I'm talking about?