Kangding has the best food options in western Sichuan, reflecting its position as the largest city on the plateau and its centuries of mixed Han-Tibetan culture. The commercial area around the main square has restaurants ranging from proper Sichuan cuisine — Kangding is far enough into the mountains that the food is somewhat milder than Chengdu's, but mapo tofu and hotpot remain staples — to Tibetan restaurants serving yak meat dishes, momos, and butter tea.
The covered market area has small stalls selling cheap Tibetan and Han food through the day and evening. For sit-down meals, the restaurants along the main shopping street serve reliable versions of standard Chinese dishes; look for places with laminated picture menus if you don't read Chinese, and expect to pay less than you would for equivalent quality in Chengdu.
Butter tea — thick, salted, with a fat content that is functional rather than indulgent at altitude — is available in Tibetan restaurants and is worth trying once. Yak butter is the cooking fat in most traditional Tibetan establishments; it has a particular smell and flavour that is acquired but genuine. Tibetan bread, baked in thick discs, is a better starting point for the uninitiated.