Kosher in seattle
As mentioned the Kosher vegetarian is in the north. It is outside the park where the Tower is located. You can take the monorail to the last stop, walk through the park, enjoy the sites especially the musical fountain if it is working, and then to the restuarant.
On the way back take the monorail to the shopping plaza station, go down with the elevator to the bottom and you can pick up the light rail directly to the airport.
It should take about 45 minutes to an hour and is a nice scenic ride