I like the Salmon Burger ($9) at Central Market Westgate. Salmon Burger isn't really the right name for it as it's not really burgery at all. It's a piece of miso glazed grilled salmon with seaweed salad and wasabi avocado spread, on a soft slightly sweet bun. It comes with fries.
Central Market Westgate
4477 S Lamar Blvd, Austin, TX