In the late 90's when I was studying in Germany, whenever there was a potluck dinner, nem thịt would be my go-to contribution. Similar to many representative Vietnamese dishes, nem (or the more familiar alias ‘spring rolls') has numerous variants across regions depending on specific local products and local habits. The recipe presented here is a Hanoi variant, in which the woodear and dried shiitake are indispensable.
Back in the days it was not easy to find these specific ingredients in German local markets, so I everything I needed, I had had to brought from home: woodear, shiitake, glass noodles. The only remotely similar option at the Asian market to the glass noodles were dried rice noodles; but they could not absorb the extra moisture in the filling so the rolls would burst while being fried. Of course I could not bring the whole grocery market with me, so with time I learnt to adapt, eg: switching white leeks for beansprouts. As I mentioned, different regions have their different versions of nem based off their own preference and what are available to them. You, too. Play around with whatever ingredients you can find, just pay attention to the overall moistness of the filling and you're good to go.
Minced lean pork shoulder
Spring onion, Onion
Pepper, Salt , Fish sauce
Soak glass noodle in cold water. Rinse and cut into 5cm length
Soak shiitake and wood-ear. Rinse and dice
Slice spring onions, dice onion and carrot
Mix all dry ingredients and 5 eggs in a large mixing bowl. Add seasoning and some oil. Mix again and let rest for 5 minutes
Wrap each small portions of the filling in a piece of rice paper and roll
Heat oil in frying pan. Fry until rolls are golden brown