You met some vietnamese friends in England, that's interesting.
I live in Vietnam and i have never gone abroad and i hope i will have chances to do that in future
If you like Nem, you can visit my blog (there're some kinds of Nem, all of them are delicious, and this is Nem which i like best )
http://vuhung91.blogspot.com/2008/05/nem_31.html
The post is short, but i think you will know more about Nem