The public do have a perception that Buddhist sangha should be vegetarians, as we promote compassion and care for all living beings, which extends to animals as well. Therefore, those new to Tibetan Buddhism usually express surprise that the monks and nuns seems to enjoy a good meal of meat! Only when they understand the history and geography of Tibet do they understand why most Tibetan sangha were brought up eating meat.
The Dalai Lama is probably the main person promoting vegetarianism in Tibet. Apart from what was quoted by ensapa, here are a few more examples of the good work the Dalai Lama has done with regards to vegetarianism:
At Kalachakra for World Peace 2006, presided over by the Dalai Lama, all the food served to the 200,000 people attending the ceremony was vegetarian. He made a speech in Tibetan, criticizing factory farming and meat consumption, and urging Tibetans to stop the trade in wild animal skins and furs.
Tibetan Volunteers for Animals (TVA) has converted over 14,000 Tibetans to vegetarianism. The new vegetarians sign a pledge never to eat meat again. Dalai Lama gave funds to TVA to print 35,000 copies of vegetarian books for free distribution. The group campaigns for vegetarianism in Tibetan settlements throughout India, Ladakh, Nepal and Sikkim. They are opening vegetarian restaurants in Tibetan communities.
Dalai Lama has repeatedly urged people to move toward a more compassionate diet. His kitchen at his residence in Dharamsala is vegetarian. He doesn't always maintain a vegetarian diet while traveling. It is reported that Tibetan doctors told him he must still eat some meat. Most Tibetan doctors are unfamiliar with vegetarianism, as are most Western doctors.
In 1993, Dalai Lama asked restaurants in Dharamsala, India, home of the world’s largest Tibetan exile community, to become vegetarian so that Tibetans could experience delicious vegetarian food and learn how to stop eating meat. As a result, several local residents became vegetarian, and because of these restaurants vegetarian foods such as tofu have become known to the Tibetan public.
Several years prior to 2006, His Holiness has requested Tibetan monks and nuns become vegetarian. Traditionally, monks and nuns would eat food that had been offered to them, including meat. It was felt that if the monks had fresh tofu to eat each day, it would provide them with the good protein source they need.
So a plan was implemented to purchase a tofu machine that would be able to provide fresh tofu daily to 3,000 monks and nuns. The intention of this project is to one day have a tofu machine in each Tibetan monastery in India and Nepal. (Arjia Rinpoche's Tofu Project TCCWOnline.org)
In 2004, Kentucky Fried Chicken announced plans to open chicken restaurants in Tibet, and in response the Dalai Lama issued the following public appeal: “On behalf of my friends at People for the Ethical Treatment of Animals (PETA), I am writing to ask that KFC abandon its plan to open restaurants in Tibet because your corporation’s support for cruelty and mass slaughter violate Tibetan values.” Thereafter, the KFC management abandoned its plans.