I had these spring rolls at a restraunt, but as you can see the outside was quite different to the 'normal' spring rolls I usually see.
The texture is light and crispy and looks 'stringy (but doesn't taste or feel that way).
I think it was quite interesting and would like to give them a shot but aren't sure what they're called to search for a recipe.
It's regular roll made with net rice wrapper
It's common wrapper in Vietnam.
Here's site when you can see the package and rolls made with it bearnakedfood
The dish you ate is called Chả giò rế. The coating is called Bánh tráng rế.
"Rế" is hisitorically a rattan or bamboo net to rest hot pans and pots after cooking.
Bánh tráng rế is made mainly from rice powder. But there are also variations which are made from a mixture of rice powder, corn powder and cassava powder. Some salt and sugar are added too.
Making Bánh tráng rế is a crossover of making rice papers and noodles. Traditionally, you have a fryer with a flat and wide surface. Soggy rice liquid will be poured into that hot surface to get steamed through tiny holes drilled from a container.
In London from a Vietnamese restaurant, I have received this variant of the spring roll.
It is called Chả Giò Rế Chiên Giòn (the "nest" variant of Chả Giò spring roll)
Beautiful Google images here :) https://www.google.com/search?q=Ch%E1%BA%A3+Gi%C3%B2+R%E1%BA%BF+Chi%C3%AAn+Gi%C3%B2n&tbm=isch
