We don't live in Norderstedt but have friends and family there, so go out for food sometimes.
Our two favourites:
Alter Reporter is a pub with very good food (by far better than normal pub grub), they have great cocktails, food specials like "all you can eat" Tapas etc., skittles alleys, a great beergarden, and the BEST service I have ever encountered anywhere.
and
China Restaurant Mongolei
Marktplatz 3
22844 Norderstedt
phone 040 55440598
(a phantastic Chinese serving a la carte or Mongolian Barbecue. The food is fresh, very tasty and for € 12,80 the barbecue is a real bargain - service also very nice and attentive, even if your kids are not into Chinese food, there's breaded chicken, chips and other stuff that kids like available)