We ate here twice on our trip to Maine - we always plan around stopping in Portland to do so. Their many Thai recipes are very vegan friendly, and I've never had "Far East Duck", a traditional Buddhist seitan dish, better anywhere else! Their wine selection is good and the atmosphere is lovely - nice interior and very couples-oriented. It's in the next block from the Portland Art Museum, so makes a great evening finish.
The neighborhood is not the best and parking can be dicey, but well worth it. Try the Thai soups.