Ürümqi is the best place in China to eat Uyghur food without making the full trip to Kashgar. The cuisine is Central Asian at its core — lamb dominates, bread is baked in a tandoor, and rice is cooked with carrots and raisins into rich polo. It is hearty, warming food built for people who spent long days on horseback or tending livestock, and it is genuinely excellent.
The Erdaoqiao area is where to go. The streets around the Grand Bazaar are lined with small family restaurants, and the smells of cumin, lamb fat, and fresh bread are a reliable guide. Laghman — thick hand-pulled noodles tossed with lamb, peppers, and tomato — is the dish to start with: simple to order, universally available, and a good measure of any kitchen's quality. Polo (the Uyghur pilaf) is best at lunchtime, when the large communal pots are freshly made. Samsa — baked triangular pastries filled with lamb and onion — make a good snack at any hour.
Han Chinese food is widely available throughout the city if you want a break. But if you are in Ürümqi, the Uyghur table is the reason to eat here.