The Muslim Quarter is behind the Drum Tower. The first thing you see behind the Tower is a food market, with sweets for sale. A small alley on the left takes you to the Big Mosque. The avenue departing from the Drum Tower is full with Muslim restaurants. Do not miss, among many other local specialties, the skewed lamb.
Good places to eat in Xian are the muslim quarters (number one), and the area around the Bell Tower. In other areas of Xian you will find local restaurants too.