I must say I love Asian food, and Vietnamese is probably amongst my favorite ones.
Until 2015 it was very difficult to find this amazing cuisine in town, except for a couple or slightly more dishes you could get in Chinese restaurants. But now, the problem is solved.
If you fancy vietnamese rolls or a nice and warm beef pho, go to the Trattoria del Vietnam: you will not be disappointed. The restaurant is just minutes from the huge Porta Palazzo market (where you can actually find come shops selling all the Asian goods you get in town).
You will be seated in a nice and new dining area (the Trattoria opened in June 2015) and you will have the chance to taste fantastic dishes from Vietnam: in the menu also some Thai dishes, but the main focus is on Viet cuisine. Try out the pho in beef or chicken broth, or taste the amazing deep fried rolls. You may have Vietnamese beer or a little bunch of Italian wines with your food: each and everyone of them is worth trying.
Service is nice and the owner will be delighted to tip you on the menu: his origin is from Vietnam but he speaks excellent Italian since he was born here. Moreover, you will appreciate the freshness of the ingredients: the owner also owns one of the first Vietnamese shops in town (a couple of blocks north in the same road), so he gets supplies on a regular basis from the homeland.