I stumbled upon this restaurant last week. I was traveling to the Spring area and looked up Vietnamese restaurants. When I saw their on-line menu, I knew I had to try them.
They have seven or eight purely vegetarian/vegan dishes. They have two different types of veg spring rolls. I tried both (yes, I went back again yesterday!) and they were delicious. The difference in the two is that one has jicama and carrots while the other does not. Both have tofu, sprouts, etc.
For a main dish I have tried both the Tofu Vermicelli and the Rock-N-Roll Tofu. Both were delicious and had very subtle flavors. Of the two, I'd say the Vermicelli was my favorite. It was loaded with veggies and the tofu was delicately flavored. I even asked if they made their own tofu because I could tell it was extremely fresh. They said they bought it daily.
I highly recommend this restaurant as an alternative. It's not often that I find this kind of vegetarian options on a mainline menu.
Oh, by the way, the staff is extremely nice and helpful. Enjoy.