Lhasa's restaurant scene runs from butter-lamp-lit Tibetan teahouses to Sichuanese hotpot palaces brought in by the wave of Chinese migration. The cooking divides broadly into three kitchens: Tibetan (thukpa noodle soups, momo dumplings, yak meat dishes, tsampa barley flour, butter tea), Chinese (Sichuanese, in particular, is everywhere), and a Nepali-Indian-Continental hybrid in the traveller restaurants near the Jokhang.
Eat at least one full meal in a Tibetan family-style teahouse — the Ani Tsankhung Nunnery's teahouse is the standby — and try the local barley beer, chang, at least once. For Western food when you've had enough yak, Dunya and the Snowland are the long-time fallbacks.