Winston Salem - Vietnamese
It sucks, but there are ZERO vietnamese restos in W-S- terrible because there is a Vietnamese community, and they work in all the Japanese restos. Which perhaps explains why there are no authentic Japanese restos in W-S either.
Head to Greensboro for vermicelli at Saigon (nowhere near the best Vietnamese I've had, which was right outside of DC), and Van Loi for Pho (excellent) as well as Pahk Side Cafe for the best and cheapest Banh Mi ever (run-down shopping center near the projects on the corner of Freeman Mill Road and Florida Street, exit 218 off the old 40, which you get to from the new 40 by following the signs to "Bryan Blvd and Downtown"- misleading, I know- but sooo worth it. Make sure you go during the daylight and bring cash as they don't take credit cards).
I've been to Xia once. I thought the food was terrible. I won't go back.
I second quazi's POV. You'll have to make the trek to GBO for good Vietnamese food.
Xia is an attractive pan-Asian restaurant and is your best alternative in W-S. Last visit both spring rolls and pho were on the menu. The food was pretty good, but IMHO simplified for American tastes and lacking some of the complexity of tastes and textures that you will find elsewhere.