Cologne has a large Turkish population and therefore lots of Turkish cuisine is on offer. There are two restaurants in a street called Weidengasse near Cologne station which present truly exceptional versions of this fine cuisine. One is called Bosporus and has a spectacular Meze assortiment and many good meat and seafood dishes from the grill. The other, Bizim, is indeed something really unique. I have been there a few times and never been disappointed. The Turkish chef and his German wife do a great job mixing oriental and french influences and serving their creations with a good variety of Turkish Wines. The Bizim is one of the top ethnic restaurants in Germany according to both the Michelin and Gault Millau guides.

For a description and reservation information of the Bizim (if the link works):

http://www.gaultmillau.de/gmd/single.php3?id=770