The muslim food could be found easily in these cities of North Chian, of course Harbin. It will be one of the best time to visit Harbin during Chinese New Year, if you would like to experience astonishing snow and ice festival.

I found the muslim food in Harbin to be fine (although I have eaten at only one or two muslim restaurants there, as it is not my preference). In Xi'an, however (where muslim food seems to be the only choice in some parts of town), I found it to be greasy and the restaurants to be a bit dirty with many underaged workers. So, muslim food is not the same all over China, in my opinion. Harbin is a very special city where many cultures come together. Have fun.