Udupi Palace serves the best south Indian food I have found in the Seattle area.
This small, humble restaurant is located near the cinema in the Crossroads Mall (not inside the mall, but alongside it).
They have opened a second location in Issaquah called Dosa Palace. I have never been there.
730 NW Gilman Blvd. Suite #C-107
Phone : (425) 369-2343