Hey you MUST MUST try the turkish Döner Kebab... You can find them everywhere in berlin...FYI in all of germany, the best Döner is in Berlin.
I would recomend going to Schloss Strasse... In this long street you will find lots of malls and restaurants. Very clean very nice ;)
After you have tried the Döner i would also recomend going to Arcaden mall (not sure wheather its spelled with a c or k) its located in Potsdamer Platz. They have a very nice chinese restaurant in the 1st floor. over 8 years ago