I wanna recommend authentic northern thai cuisine "Khao Soi.=Curry Noodle!
Usually it's not vegetarian dish, but we can order vegetarian khao soi at
food court of Thai Vegetarian Society(JJ)".
When I was in Chiang mai (more than 10 years ago!), I often had it.
(I wasn't vegetarian or vegan st that time so I had Chicken Khao Soi.
But I think Vegetarian one is also delicious for both vegans and non-vegans...
You can try it at food court of thai vegetarian society.